| /*- |
| * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 |
| * The Regents of the University of California. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * 4. Neither the name of the University nor the names of its contributors |
| * may be used to endorse or promote products derived from this software |
| * without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| * |
| * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95 |
| */ |
| |
| #include <sys/bsd_cdefs.h> |
| //__FBSDID("$FreeBSD$"); |
| |
| #include "bsd_opt_ipfw.h" /* for ipfw_fwd */ |
| #include "bsd_opt_inet.h" |
| #include "bsd_opt_inet6.h" |
| #include "bsd_opt_ipsec.h" |
| #include "bsd_opt_tcpdebug.h" |
| |
| #include <sys/bsd_param.h> |
| #include <sys/bsd_kernel.h> |
| #include <sys/bsd_malloc.h> |
| #include <sys/bsd_mbuf.h> |
| ////#include <sys/bsd_proc.h> /* for proc0 declaration */ |
| #include <sys/bsd_protosw.h> |
| //#include <sys/bsd_signalvar.h> |
| #include <sys/bsd_socket.h> |
| #include <sys/bsd_socketvar.h> |
| //baoyg//#include <sys/bsd_sysctl.h> |
| #include <sys/bsd_syslog.h> |
| #include <sys/bsd_systm.h> |
| |
| #include <machine/bsd_cpu.h> /* before tcp_seq.h, for tcp_random18() */ |
| |
| #include <vm/bsd_uma.h> |
| |
| #include <net/bsd_if.h> |
| #include <net/bsd_route.h> |
| #include <net/bsd_vnet.h> |
| |
| #define TCPSTATES /* for logging */ |
| |
| #include <netinet/bsd_in.h> |
| #include <netinet/bsd_in_pcb.h> |
| #include <netinet/bsd_in_systm.h> |
| #include <netinet/bsd_in_var.h> |
| #include <netinet/bsd_ip.h> |
| #include <netinet/bsd_ip_icmp.h> /* required for icmp_var.h */ |
| #include <netinet/bsd_icmp_var.h> /* for ICMP_BANDLIM */ |
| #include <netinet/bsd_ip_var.h> |
| #include <netinet/bsd_ip_options.h> |
| //#include <netinet/bsd_ip6.h> |
| //#include <netinet/bsd_icmp6.h> |
| //#include <netinet6/bsd_in6_pcb.h> |
| //#include <netinet6/bsd_ip6_var.h> |
| //#include <netinet6/bsd_nd6.h> |
| #include <netinet/bsd_tcp.h> |
| #include <netinet/bsd_tcp_fsm.h> |
| #include <netinet/bsd_tcp_seq.h> |
| #include <netinet/bsd_tcp_timer.h> |
| #include <netinet/bsd_tcp_var.h> |
| //#include <netinet6/bsd_tcp6_var.h> |
| #include <netinet/bsd_tcpip.h> |
| #include <netinet/bsd_tcp_syncache.h> |
| #ifdef TCPDEBUG |
| #include <netinet/bsd_tcp_debug.h> |
| #endif /* TCPDEBUG */ |
| |
| #ifdef IPSEC |
| #include <netipsec/bsd_ipsec.h> |
| #include <netipsec/bsd_ipsec6.h> |
| #endif /*IPSEC*/ |
| |
| #include <machine/bsd_in_cksum.h> |
| |
| #ifdef MAC |
| #include <security/mac/bsd_mac_framework.h> |
| #endif |
| |
| #include "uptcp_statis.h" |
| |
| extern int bsd_hz; |
| extern int bsd_ticks; |
| |
| static const int tcprexmtthresh = 3; |
| |
| VNET_DEFINE(struct tcpstat, tcpstat); |
| VNET_DEFINE(int, blackhole); |
| VNET_DEFINE(int, tcp_delack_enabled); |
| VNET_DEFINE(int, drop_synfin); |
| VNET_DEFINE(int, tcp_do_rfc3042); |
| VNET_DEFINE(int, tcp_do_rfc3390); |
| VNET_DEFINE(int, tcp_do_ecn); |
| VNET_DEFINE(int, tcp_ecn_maxretries); |
| VNET_DEFINE(int, tcp_insecure_rst); |
| VNET_DEFINE(int, tcp_do_autorcvbuf); |
| VNET_DEFINE(int, tcp_autorcvbuf_inc); |
| VNET_DEFINE(int, tcp_autorcvbuf_max); |
| VNET_DEFINE(int, tcp_do_rfc3465); |
| VNET_DEFINE(int, tcp_abc_l_var); |
| /* |
| SYSCTL_VNET_STRUCT(_net_inet_tcp, TCPCTL_STATS, stats, CTLFLAG_RW, |
| &VNET_NAME(tcpstat), tcpstat, |
| "TCP statistics (struct tcpstat, netinet/tcp_var.h)"); |
| */ |
| int tcp_log_in_vain = 0; |
| /*SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_RW, |
| &tcp_log_in_vain, 0, |
| "Log all incoming TCP segments to closed ports"); |
| |
| SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, blackhole, CTLFLAG_RW, |
| &VNET_NAME(blackhole), 0, |
| "Do not send RST on segments to closed ports"); |
| |
| SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_RW, |
| &VNET_NAME(tcp_delack_enabled), 0, |
| "Delay ACK to try and piggyback it onto a data packet"); |
| |
| SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, drop_synfin, CTLFLAG_RW, |
| &VNET_NAME(drop_synfin), 0, |
| "Drop TCP packets with SYN+FIN set"); |
| |
| SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, rfc3042, CTLFLAG_RW, |
| &VNET_NAME(tcp_do_rfc3042), 0, |
| "Enable RFC 3042 (Limited Transmit)"); |
| |
| SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, rfc3390, CTLFLAG_RW, |
| &VNET_NAME(tcp_do_rfc3390), 0, |
| "Enable RFC 3390 (Increasing TCP's Initial Congestion Window)"); |
| |
| SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, rfc3465, CTLFLAG_RW, |
| &VNET_NAME(tcp_do_rfc3465), 0, |
| "Enable RFC 3465 (Appropriate Byte Counting)"); |
| |
| SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, abc_l_var, CTLFLAG_RW, |
| &VNET_NAME(tcp_abc_l_var), 2, |
| "Cap the max cwnd increment during slow-start to this number of segments"); |
| |
| SYSCTL_NODE(_net_inet_tcp, OID_AUTO, ecn, CTLFLAG_RW, 0, "TCP ECN"); |
| |
| SYSCTL_VNET_INT(_net_inet_tcp_ecn, OID_AUTO, enable, CTLFLAG_RW, |
| &VNET_NAME(tcp_do_ecn), 0, |
| "TCP ECN support"); |
| |
| SYSCTL_VNET_INT(_net_inet_tcp_ecn, OID_AUTO, maxretries, CTLFLAG_RW, |
| &VNET_NAME(tcp_ecn_maxretries), 0, |
| "Max retries before giving up on ECN"); |
| |
| SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, insecure_rst, CTLFLAG_RW, |
| &VNET_NAME(tcp_insecure_rst), 0, |
| "Follow the old (insecure) criteria for accepting RST packets"); |
| |
| SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, recvbuf_auto, CTLFLAG_RW, |
| &VNET_NAME(tcp_do_autorcvbuf), 0, |
| "Enable automatic receive buffer sizing"); |
| |
| SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, recvbuf_inc, CTLFLAG_RW, |
| &VNET_NAME(tcp_autorcvbuf_inc), 0, |
| "Incrementor step size of automatic receive buffer"); |
| |
| SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, recvbuf_max, CTLFLAG_RW, |
| &VNET_NAME(tcp_autorcvbuf_max), 0, |
| "Max size of automatic receive buffer");*/ |
| |
| int tcp_read_locking = 1; |
| /*SYSCTL_INT(_net_inet_tcp, OID_AUTO, read_locking, CTLFLAG_RW, |
| &tcp_read_locking, 0, "Enable read locking strategy"); |
| */ |
| VNET_DEFINE(struct inpcbhead, tcb); |
| VNET_DEFINE(struct inpcbinfo, tcbinfo); |
| #define tcb6 tcb /* for KAME src sync over BSD*'s */ |
| |
| static void tcp_dooptions(struct tcpopt *, u_char *, int, int); |
| static void tcp_do_segment(struct mbuf *, struct tcphdr *, |
| struct socket *, struct tcpcb *, int, int, uint8_t, |
| int); |
| static void tcp_dropwithreset(struct mbuf *, struct tcphdr *, |
| struct tcpcb *, int, int); |
| static void tcp_pulloutofband(struct socket *, |
| struct tcphdr *, struct mbuf *, int); |
| static void tcp_xmit_timer(struct tcpcb *, int); |
| static void tcp_newreno_partial_ack(struct tcpcb *, struct tcphdr *); |
| static void inline |
| tcp_congestion_exp(struct tcpcb *); |
| |
| /* |
| * Kernel module interface for updating tcpstat. The argument is an index |
| * into tcpstat treated as an array of u_long. While this encodes the |
| * general layout of tcpstat into the caller, it doesn't encode its location, |
| * so that future changes to add, for example, per-CPU stats support won't |
| * cause binary compatibility problems for kernel modules. |
| */ |
| void |
| kmod_tcpstat_inc(int statnum) |
| { |
| |
| (*((u_long *)&V_tcpstat + statnum))++; |
| } |
| |
| static void inline |
| tcp_congestion_exp(struct tcpcb *tp) |
| { |
| u_int win; |
| |
| win = min(tp->snd_wnd, tp->snd_cwnd) / |
| 2 / tp->t_maxseg; |
| if (win < 2) |
| win = 2; |
| tp->snd_ssthresh = win * tp->t_maxseg; |
| ENTER_FASTRECOVERY(tp); |
| tp->snd_recover = tp->snd_max; |
| if (tp->t_flags & TF_ECN_PERMIT) |
| tp->t_flags |= TF_ECN_SND_CWR; |
| } |
| |
| /* Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint. */ |
| #ifdef INET6 |
| #define ND6_HINT(tp) \ |
| do { \ |
| if ((tp) && (tp)->t_inpcb && \ |
| ((tp)->t_inpcb->inp_vflag & INP_IPV6) != 0) \ |
| nd6_nud_hint(NULL, NULL, 0); \ |
| } while (0) |
| #else |
| #define ND6_HINT(tp) |
| #endif |
| |
| /* |
| * Indicate whether this ack should be delayed. We can delay the ack if |
| * - there is no delayed ack timer in progress and |
| * - our last ack wasn't a 0-sized window. We never want to delay |
| * the ack that opens up a 0-sized window and |
| * - delayed acks are enabled or |
| * - this is a half-synchronized T/TCP connection. |
| */ |
| #define DELAY_ACK(tp) \ |
| ((!tcp_timer_active(tp, TT_DELACK) && \ |
| (tp->t_flags & TF_RXWIN0SENT) == 0) && \ |
| (V_tcp_delack_enabled || (tp->t_flags & TF_NEEDSYN))) |
| |
| /* |
| * TCP input handling is split into multiple parts: |
| * tcp6_input is a thin wrapper around tcp_input for the extended |
| * ip6_protox[] call format in ip6_input |
| * tcp_input handles primary segment validation, inpcb lookup and |
| * SYN processing on listen sockets |
| * tcp_do_segment processes the ACK and text of the segment for |
| * establishing, established and closing connections |
| */ |
| #ifdef INET6 |
| int |
| tcp6_input(struct mbuf **mp, int *offp, int proto) |
| { |
| struct mbuf *m = *mp; |
| struct in6_ifaddr *ia6; |
| |
| IP6_EXTHDR_CHECK(m, *offp, sizeof(struct tcphdr), IPPROTO_DONE); |
| |
| /* |
| * draft-itojun-ipv6-tcp-to-anycast |
| * better place to put this in? |
| */ |
| ia6 = ip6_getdstifaddr(m); |
| if (ia6 && (ia6->ia6_flags & IN6_IFF_ANYCAST)) { |
| struct ip6_hdr *ip6; |
| |
| ifa_free(&ia6->ia_ifa); |
| ip6 = mtod(m, struct ip6_hdr *); |
| icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, |
| (caddr_t)&ip6->ip6_dst - (caddr_t)ip6); |
| return IPPROTO_DONE; |
| } |
| |
| tcp_input(m, *offp); |
| return IPPROTO_DONE; |
| } |
| #endif |
| |
| void |
| tcp_input(struct mbuf *m, int off0) |
| { |
| struct tcphdr *th; |
| struct ip *ip = NULL; |
| struct ipovly *ipov; |
| struct inpcb *inp = NULL; |
| struct tcpcb *tp = NULL; |
| struct socket *so = NULL; |
| u_char *optp = NULL; |
| int optlen = 0; |
| int len, tlen, off; |
| int drop_hdrlen; |
| int thflags; |
| int rstreason = 0; /* For badport_bandlim accounting purposes */ |
| uint8_t iptos; |
| #ifdef IPFIREWALL_FORWARD |
| struct m_tag *fwd_tag; |
| #endif |
| #ifdef INET6 |
| struct ip6_hdr *ip6 = NULL; |
| int isipv6; |
| #else |
| const void *ip6 = NULL; |
| const int isipv6 = 0; |
| #endif |
| struct tcpopt to; /* options in this segment */ |
| char *s = NULL; /* address and port logging */ |
| int ti_locked; |
| #define TI_UNLOCKED 1 |
| #define TI_RLOCKED 2 |
| #define TI_WLOCKED 3 |
| |
| #ifdef TCPDEBUG |
| /* |
| * The size of tcp_saveipgen must be the size of the max ip header, |
| * now IPv6. |
| */ |
| u_char tcp_saveipgen[IP6_HDR_LEN]; |
| struct tcphdr tcp_savetcp; |
| short ostate = 0; |
| #endif |
| |
| #ifdef INET6 |
| isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? 1 : 0; |
| #endif |
| |
| to.to_flags = 0; |
| TCPSTAT_INC(tcps_rcvtotal); |
| |
| |
| if (isipv6) { |
| #ifdef INET6 |
| /* IP6_EXTHDR_CHECK() is already done at tcp6_input(). */ |
| ip6 = mtod(m, struct ip6_hdr *); |
| tlen = sizeof(*ip6) + ntohs(ip6->ip6_plen) - off0; |
| if (in6_cksum(m, IPPROTO_TCP, off0, tlen)) { |
| TCPSTAT_INC(tcps_rcvbadsum); |
| goto drop; |
| } |
| th = (struct tcphdr *)((caddr_t)ip6 + off0); |
| |
| /* |
| * Be proactive about unspecified IPv6 address in source. |
| * As we use all-zero to indicate unbounded/unconnected pcb, |
| * unspecified IPv6 address can be used to confuse us. |
| * |
| * Note that packets with unspecified IPv6 destination is |
| * already dropped in ip6_input. |
| */ |
| if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { |
| /* XXX stat */ |
| goto drop; |
| } |
| #else |
| th = NULL; /* XXX: Avoid compiler warning. */ |
| #endif |
| } else { |
| /* |
| * Get IP and TCP header together in first mbuf. |
| * Note: IP leaves IP header in first mbuf. |
| */ |
| if (off0 > sizeof (struct ip)) { |
| ip_stripoptions(m, (struct mbuf *)0); |
| off0 = sizeof(struct ip); |
| } |
| if (m->m_len < sizeof (struct tcpiphdr)) { |
| if ((m = m_pullup(m, sizeof (struct tcpiphdr))) |
| == NULL) { |
| TCPSTAT_INC(tcps_rcvshort); |
| return; |
| } |
| } |
| ip = mtod(m, struct ip *); |
| ipov = (struct ipovly *)ip; |
| th = (struct tcphdr *)((caddr_t)ip + off0); |
| tlen = ip->ip_len; |
| |
| if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) { |
| if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) |
| th->th_sum = m->m_pkthdr.csum_data; |
| else |
| th->th_sum = in_pseudo(ip->ip_src.s_addr, |
| ip->ip_dst.s_addr, |
| htonl(m->m_pkthdr.csum_data + |
| ip->ip_len + |
| IPPROTO_TCP)); |
| th->th_sum ^= 0xffff; |
| #ifdef TCPDEBUG |
| ipov->ih_len = (u_short)tlen; |
| ipov->ih_len = htons(ipov->ih_len); |
| #endif |
| } else { |
| /* |
| * Checksum extended TCP header and data. |
| */ |
| len = sizeof (struct ip) + tlen; |
| bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); |
| ipov->ih_len = (u_short)tlen; |
| ipov->ih_len = htons(ipov->ih_len); |
| th->th_sum = in_cksum(m, len); |
| } |
| #ifndef NIF_CSUM_ENABLE |
| th->th_sum = 0; |
| #endif |
| |
| if (th->th_sum) { |
| TCPSTAT_INC(tcps_rcvbadsum); |
| goto drop; |
| } |
| /* Re-initialization for later version check */ |
| ip->ip_v = IPVERSION; |
| } |
| |
| #ifdef INET6 |
| if (isipv6) |
| iptos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; |
| else |
| #endif |
| iptos = ip->ip_tos; |
| |
| /* |
| * Check that TCP offset makes sense, |
| * pull out TCP options and adjust length. XXX |
| */ |
| off = th->th_off << 2; |
| if (off < sizeof (struct tcphdr) || off > tlen) { |
| TCPSTAT_INC(tcps_rcvbadoff); |
| goto drop; |
| } |
| tlen -= off; /* tlen is used instead of ti->ti_len */ |
| if (off > sizeof (struct tcphdr)) { |
| if (isipv6) { |
| #ifdef INET6 |
| IP6_EXTHDR_CHECK(m, off0, off, ); |
| ip6 = mtod(m, struct ip6_hdr *); |
| th = (struct tcphdr *)((caddr_t)ip6 + off0); |
| #endif |
| } else { |
| if (m->m_len < sizeof(struct ip) + off) { |
| if ((m = m_pullup(m, sizeof (struct ip) + off)) |
| == NULL) { |
| TCPSTAT_INC(tcps_rcvshort); |
| return; |
| } |
| ip = mtod(m, struct ip *); |
| ipov = (struct ipovly *)ip; |
| th = (struct tcphdr *)((caddr_t)ip + off0); |
| } |
| } |
| optlen = off - sizeof (struct tcphdr); |
| optp = (u_char *)(th + 1); |
| } |
| thflags = th->th_flags; |
| |
| /* |
| * Convert TCP protocol specific fields to host format. |
| */ |
| th->th_seq = ntohl(th->th_seq); |
| th->th_ack = ntohl(th->th_ack); |
| th->th_win = ntohs(th->th_win); |
| th->th_urp = ntohs(th->th_urp); |
| |
| /* |
| * Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options. |
| */ |
| drop_hdrlen = off0 + off; |
| |
| /* |
| * Locate pcb for segment, which requires a lock on tcbinfo. |
| * Optimisticaly acquire a global read lock rather than a write lock |
| * unless header flags necessarily imply a state change. There are |
| * two cases where we might discover later we need a write lock |
| * despite the flags: ACKs moving a connection out of the syncache, |
| * and ACKs for a connection in TIMEWAIT. |
| */ |
| if ((thflags & (TH_SYN | TH_FIN | TH_RST)) != 0 || |
| tcp_read_locking == 0) { |
| INP_INFO_WLOCK(&V_tcbinfo); |
| ti_locked = TI_WLOCKED; |
| } else { |
| INP_INFO_RLOCK(&V_tcbinfo); |
| ti_locked = TI_RLOCKED; |
| } |
| |
| findpcb: |
| #ifdef INVARIANTS |
| if (ti_locked == TI_RLOCKED) |
| INP_INFO_RLOCK_ASSERT(&V_tcbinfo); |
| else if (ti_locked == TI_WLOCKED) |
| INP_INFO_WLOCK_ASSERT(&V_tcbinfo); |
| else |
| panic("%s: findpcb ti_locked %d\n", __func__, ti_locked); |
| #endif |
| |
| #ifdef IPFIREWALL_FORWARD |
| /* |
| * Grab info from PACKET_TAG_IPFORWARD tag prepended to the chain. |
| */ |
| fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL); |
| |
| if (fwd_tag != NULL && isipv6 == 0) { /* IPv6 support is not yet */ |
| struct sockaddr_in *next_hop; |
| |
| next_hop = (struct sockaddr_in *)(fwd_tag+1); |
| /* |
| * Transparently forwarded. Pretend to be the destination. |
| * already got one like this? |
| */ |
| inp = in_pcblookup_hash(&V_tcbinfo, |
| ip->ip_src, th->th_sport, |
| ip->ip_dst, th->th_dport, |
| 0, m->m_pkthdr.rcvif); |
| if (!inp) { |
| /* It's new. Try to find the ambushing socket. */ |
| inp = in_pcblookup_hash(&V_tcbinfo, |
| ip->ip_src, th->th_sport, |
| next_hop->sin_addr, |
| next_hop->sin_port ? |
| ntohs(next_hop->sin_port) : |
| th->th_dport, |
| INPLOOKUP_WILDCARD, |
| m->m_pkthdr.rcvif); |
| } |
| /* Remove the tag from the packet. We don't need it anymore. */ |
| m_tag_delete(m, fwd_tag); |
| } else |
| #endif /* IPFIREWALL_FORWARD */ |
| { |
| if (isipv6) { |
| #ifdef INET6 |
| inp = in6_pcblookup_hash(&V_tcbinfo, |
| &ip6->ip6_src, th->th_sport, |
| &ip6->ip6_dst, th->th_dport, |
| INPLOOKUP_WILDCARD, |
| m->m_pkthdr.rcvif); |
| #endif |
| } else |
| inp = in_pcblookup_hash(&V_tcbinfo, |
| ip->ip_src, th->th_sport, |
| ip->ip_dst, th->th_dport, |
| INPLOOKUP_WILDCARD, |
| m->m_pkthdr.rcvif); |
| } |
| |
| /* |
| * If the INPCB does not exist then all data in the incoming |
| * segment is discarded and an appropriate RST is sent back. |
| * XXX MRT Send RST using which routing table? |
| */ |
| if (inp == NULL) { |
| /* |
| * Log communication attempts to ports that are not |
| * in use. |
| */ |
| if ((tcp_log_in_vain == 1 && (thflags & TH_SYN)) || |
| tcp_log_in_vain == 2) { |
| if ((s = tcp_log_addrs(NULL, th, (void *)ip, ip6))) |
| bsd_log(LOG_INFO, "%s; %s: Connection attempt " |
| "to closed port\n", s, __func__); |
| } |
| /* |
| * When blackholing do not respond with a RST but |
| * completely ignore the segment and drop it. |
| */ |
| if ((V_blackhole == 1 && (thflags & TH_SYN)) || |
| V_blackhole == 2) |
| goto dropunlock; |
| |
| rstreason = BANDLIM_RST_CLOSEDPORT; |
| goto dropwithreset; |
| } |
| INP_WLOCK(inp); |
| if (!(inp->inp_flags & INP_HW_FLOWID) |
| && (m->m_flags & M_FLOWID) |
| && ((inp->inp_socket == NULL) |
| || !(inp->inp_socket->so_options & SO_ACCEPTCONN))) { |
| inp->inp_flags |= INP_HW_FLOWID; |
| inp->inp_flags &= ~INP_SW_FLOWID; |
| inp->inp_flowid = m->m_pkthdr.flowid; |
| } |
| #ifdef IPSEC |
| #ifdef INET6 |
| if (isipv6 && ipsec6_in_reject(m, inp)) { |
| V_ipsec6stat.in_polvio++; |
| goto dropunlock; |
| } else |
| #endif /* INET6 */ |
| if (ipsec4_in_reject(m, inp) != 0) { |
| V_ipsec4stat.in_polvio++; |
| goto dropunlock; |
| } |
| #endif /* IPSEC */ |
| |
| /* |
| * Check the minimum TTL for socket. |
| */ |
| if (inp->inp_ip_minttl != 0) { |
| #ifdef INET6 |
| if (isipv6 && inp->inp_ip_minttl > ip6->ip6_hlim) |
| goto dropunlock; |
| else |
| #endif |
| if (inp->inp_ip_minttl > ip->ip_ttl) |
| goto dropunlock; |
| } |
| |
| /* |
| * A previous connection in TIMEWAIT state is supposed to catch stray |
| * or duplicate segments arriving late. If this segment was a |
| * legitimate new connection attempt the old INPCB gets removed and |
| * we can try again to find a listening socket. |
| * |
| * At this point, due to earlier optimism, we may hold a read lock on |
| * the inpcbinfo, rather than a write lock. If so, we need to |
| * upgrade, or if that fails, acquire a reference on the inpcb, drop |
| * all locks, acquire a global write lock, and then re-acquire the |
| * inpcb lock. We may at that point discover that another thread has |
| * tried to free the inpcb, in which case we need to loop back and |
| * try to find a new inpcb to deliver to. |
| */ |
| relocked: |
| if (inp->inp_flags & INP_TIMEWAIT) { |
| KASSERT(ti_locked == TI_RLOCKED || ti_locked == TI_WLOCKED, |
| ("%s: INP_TIMEWAIT ti_locked %d", __func__, ti_locked)); |
| |
| if (ti_locked == TI_RLOCKED) { |
| if (rw_try_upgrade(&V_tcbinfo.ipi_lock) == 0) { |
| in_pcbref(inp); |
| INP_WUNLOCK(inp); |
| INP_INFO_RUNLOCK(&V_tcbinfo); |
| INP_INFO_WLOCK(&V_tcbinfo); |
| ti_locked = TI_WLOCKED; |
| INP_WLOCK(inp); |
| if (in_pcbrele(inp)) { |
| inp = NULL; |
| goto findpcb; |
| } |
| } else |
| ti_locked = TI_WLOCKED; |
| } |
| INP_INFO_WLOCK_ASSERT(&V_tcbinfo); |
| |
| if (thflags & TH_SYN) |
| tcp_dooptions(&to, optp, optlen, TO_SYN); |
| /* |
| * NB: tcp_twcheck unlocks the INP and frees the mbuf. |
| */ |
| if (tcp_twcheck(inp, &to, th, m, tlen)) |
| goto findpcb; |
| INP_INFO_WUNLOCK(&V_tcbinfo); |
| return; |
| } |
| /* |
| * The TCPCB may no longer exist if the connection is winding |
| * down or it is in the CLOSED state. Either way we drop the |
| * segment and send an appropriate response. |
| */ |
| tp = intotcpcb(inp); |
| if (tp == NULL || tp->t_state == TCPS_CLOSED) { |
| rstreason = BANDLIM_RST_CLOSEDPORT; |
| goto dropwithreset; |
| } |
| |
| /* |
| * We've identified a valid inpcb, but it could be that we need an |
| * inpcbinfo write lock and have only a read lock. In this case, |
| * attempt to upgrade/relock using the same strategy as the TIMEWAIT |
| * case above. If we relock, we have to jump back to 'relocked' as |
| * the connection might now be in TIMEWAIT. |
| */ |
| if (tp->t_state != TCPS_ESTABLISHED || |
| (thflags & (TH_SYN | TH_FIN | TH_RST)) != 0 || |
| tcp_read_locking == 0) { |
| KASSERT(ti_locked == TI_RLOCKED || ti_locked == TI_WLOCKED, |
| ("%s: upgrade check ti_locked %d", __func__, ti_locked)); |
| |
| if (ti_locked == TI_RLOCKED) { |
| if (rw_try_upgrade(&V_tcbinfo.ipi_lock) == 0) { |
| in_pcbref(inp); |
| INP_WUNLOCK(inp); |
| INP_INFO_RUNLOCK(&V_tcbinfo); |
| INP_INFO_WLOCK(&V_tcbinfo); |
| ti_locked = TI_WLOCKED; |
| INP_WLOCK(inp); |
| if (in_pcbrele(inp)) { |
| inp = NULL; |
| goto findpcb; |
| } |
| goto relocked; |
| } else |
| ti_locked = TI_WLOCKED; |
| } |
| INP_INFO_WLOCK_ASSERT(&V_tcbinfo); |
| } |
| |
| #ifdef MAC |
| INP_WLOCK_ASSERT(inp); |
| if (mac_inpcb_check_deliver(inp, m)) |
| goto dropunlock; |
| #endif |
| so = inp->inp_socket; |
| KASSERT(so != NULL, ("%s: so == NULL", __func__)); |
| #ifdef TCPDEBUG |
| if (so->so_options & SO_DEBUG) { |
| ostate = tp->t_state; |
| if (isipv6) { |
| #ifdef INET6 |
| bcopy((char *)ip6, (char *)tcp_saveipgen, sizeof(*ip6)); |
| #endif |
| } else |
| bcopy((char *)ip, (char *)tcp_saveipgen, sizeof(*ip)); |
| tcp_savetcp = *th; |
| } |
| #endif |
| /* |
| * When the socket is accepting connections (the INPCB is in LISTEN |
| * state) we look into the SYN cache if this is a new connection |
| * attempt or the completion of a previous one. |
| */ |
| if (so->so_options & SO_ACCEPTCONN) { |
| struct in_conninfo inc; |
| |
| KASSERT(tp->t_state == TCPS_LISTEN, ("%s: so accepting but " |
| "tp not listening", __func__)); |
| |
| bzero(&inc, sizeof(inc)); |
| #ifdef INET6 |
| if (isipv6) { |
| inc.inc_flags |= INC_ISIPV6; |
| inc.inc6_faddr = ip6->ip6_src; |
| inc.inc6_laddr = ip6->ip6_dst; |
| } else |
| #endif |
| { |
| inc.inc_faddr = ip->ip_src; |
| inc.inc_laddr = ip->ip_dst; |
| } |
| inc.inc_fport = th->th_sport; |
| inc.inc_lport = th->th_dport; |
| inc.inc_fibnum = so->so_fibnum; |
| |
| /* |
| * Check for an existing connection attempt in syncache if |
| * the flag is only ACK. A successful lookup creates a new |
| * socket appended to the listen queue in SYN_RECEIVED state. |
| */ |
| if ((thflags & (TH_RST|TH_ACK|TH_SYN)) == TH_ACK) { |
| /* |
| * Parse the TCP options here because |
| * syncookies need access to the reflected |
| * timestamp. |
| */ |
| tcp_dooptions(&to, optp, optlen, 0); |
| /* |
| * NB: syncache_expand() doesn't unlock |
| * inp and tcpinfo locks. |
| */ |
| if (!syncache_expand(&inc, &to, th, &so, m)) { |
| /* |
| * No syncache entry or ACK was not |
| * for our SYN/ACK. Send a RST. |
| * NB: syncache did its own logging |
| * of the failure cause. |
| */ |
| rstreason = BANDLIM_RST_OPENPORT; |
| goto dropwithreset; |
| } |
| if (so == NULL) { |
| /* |
| * We completed the 3-way handshake |
| * but could not allocate a socket |
| * either due to memory shortage, |
| * listen queue length limits or |
| * global socket limits. Send RST |
| * or wait and have the remote end |
| * retransmit the ACK for another |
| * try. |
| */ |
| if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) |
| bsd_log(LOG_DEBUG, "%s; %s: Listen socket: " |
| "Socket allocation failed due to " |
| "limits or memory shortage, %s\n", |
| s, __func__, |
| V_tcp_sc_rst_sock_fail ? |
| "sending RST" : "try again"); |
| if (V_tcp_sc_rst_sock_fail) { |
| rstreason = BANDLIM_UNLIMITED; |
| goto dropwithreset; |
| } else |
| goto dropunlock; |
| } |
| /* |
| * Socket is created in state SYN_RECEIVED. |
| * Unlock the listen socket, lock the newly |
| * created socket and update the tp variable. |
| */ |
| INP_WUNLOCK(inp); /* listen socket */ |
| inp = sotoinpcb(so); |
| INP_WLOCK(inp); /* new connection */ |
| tp = intotcpcb(inp); |
| KASSERT(tp->t_state == TCPS_SYN_RECEIVED, |
| ("%s: ", __func__)); |
| /* |
| * Process the segment and the data it |
| * contains. tcp_do_segment() consumes |
| * the mbuf chain and unlocks the inpcb. |
| */ |
| tcp_do_segment(m, th, so, tp, drop_hdrlen, tlen, |
| iptos, ti_locked); |
| |
| INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); |
| return; |
| } |
| /* |
| * Segment flag validation for new connection attempts: |
| * |
| * Our (SYN|ACK) response was rejected. |
| * Check with syncache and remove entry to prevent |
| * retransmits. |
| * |
| * NB: syncache_chkrst does its own logging of failure |
| * causes. |
| */ |
| if (thflags & TH_RST) { |
| syncache_chkrst(&inc, th); |
| goto dropunlock; |
| } |
| /* |
| * We can't do anything without SYN. |
| */ |
| if ((thflags & TH_SYN) == 0) { |
| if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) |
| bsd_log(LOG_DEBUG, "%s; %s: Listen socket: " |
| "SYN is missing, segment ignored\n", |
| s, __func__); |
| TCPSTAT_INC(tcps_badsyn); |
| goto dropunlock; |
| } |
| /* |
| * (SYN|ACK) is bogus on a listen socket. |
| */ |
| if (thflags & TH_ACK) { |
| if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) |
| bsd_log(LOG_DEBUG, "%s; %s: Listen socket: " |
| "SYN|ACK invalid, segment rejected\n", |
| s, __func__); |
| syncache_badack(&inc); /* XXX: Not needed! */ |
| TCPSTAT_INC(tcps_badsyn); |
| rstreason = BANDLIM_RST_OPENPORT; |
| goto dropwithreset; |
| } |
| /* |
| * If the drop_synfin option is enabled, drop all |
| * segments with both the SYN and FIN bits set. |
| * This prevents e.g. nmap from identifying the |
| * TCP/IP stack. |
| * XXX: Poor reasoning. nmap has other methods |
| * and is constantly refining its stack detection |
| * strategies. |
| * XXX: This is a violation of the TCP specification |
| * and was used by RFC1644. |
| */ |
| if ((thflags & TH_FIN) && V_drop_synfin) { |
| if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) |
| bsd_log(LOG_DEBUG, "%s; %s: Listen socket: " |
| "SYN|FIN segment ignored (based on " |
| "sysctl setting)\n", s, __func__); |
| TCPSTAT_INC(tcps_badsyn); |
| goto dropunlock; |
| } |
| /* |
| * Segment's flags are (SYN) or (SYN|FIN). |
| * |
| * TH_PUSH, TH_URG, TH_ECE, TH_CWR are ignored |
| * as they do not affect the state of the TCP FSM. |
| * The data pointed to by TH_URG and th_urp is ignored. |
| */ |
| KASSERT((thflags & (TH_RST|TH_ACK)) == 0, |
| ("%s: Listen socket: TH_RST or TH_ACK set", __func__)); |
| KASSERT(thflags & (TH_SYN), |
| ("%s: Listen socket: TH_SYN not set", __func__)); |
| #ifdef INET6 |
| /* |
| * If deprecated address is forbidden, |
| * we do not accept SYN to deprecated interface |
| * address to prevent any new inbound connection from |
| * getting established. |
| * When we do not accept SYN, we send a TCP RST, |
| * with deprecated source address (instead of dropping |
| * it). We compromise it as it is much better for peer |
| * to send a RST, and RST will be the final packet |
| * for the exchange. |
| * |
| * If we do not forbid deprecated addresses, we accept |
| * the SYN packet. RFC2462 does not suggest dropping |
| * SYN in this case. |
| * If we decipher RFC2462 5.5.4, it says like this: |
| * 1. use of deprecated addr with existing |
| * communication is okay - "SHOULD continue to be |
| * used" |
| * 2. use of it with new communication: |
| * (2a) "SHOULD NOT be used if alternate address |
| * with sufficient scope is available" |
| * (2b) nothing mentioned otherwise. |
| * Here we fall into (2b) case as we have no choice in |
| * our source address selection - we must obey the peer. |
| * |
| * The wording in RFC2462 is confusing, and there are |
| * multiple description text for deprecated address |
| * handling - worse, they are not exactly the same. |
| * I believe 5.5.4 is the best one, so we follow 5.5.4. |
| */ |
| if (isipv6 && !V_ip6_use_deprecated) { |
| struct in6_ifaddr *ia6; |
| |
| ia6 = ip6_getdstifaddr(m); |
| if (ia6 != NULL && |
| (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { |
| ifa_free(&ia6->ia_ifa); |
| if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) |
| bsd_log(LOG_DEBUG, "%s; %s: Listen socket: " |
| "Connection attempt to deprecated " |
| "IPv6 address rejected\n", |
| s, __func__); |
| rstreason = BANDLIM_RST_OPENPORT; |
| goto dropwithreset; |
| } |
| ifa_free(&ia6->ia_ifa); |
| } |
| #endif |
| /* |
| * Basic sanity checks on incoming SYN requests: |
| * Don't respond if the destination is a link layer |
| * broadcast according to RFC1122 4.2.3.10, p. 104. |
| * If it is from this socket it must be forged. |
| * Don't respond if the source or destination is a |
| * global or subnet broad- or multicast address. |
| * Note that it is quite possible to receive unicast |
| * link-layer packets with a broadcast IP address. Use |
| * in_broadcast() to find them. |
| */ |
| if (m->m_flags & (M_BCAST|M_MCAST)) { |
| if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) |
| bsd_log(LOG_DEBUG, "%s; %s: Listen socket: " |
| "Connection attempt from broad- or multicast " |
| "link layer address ignored\n", s, __func__); |
| goto dropunlock; |
| } |
| if (isipv6) { |
| #ifdef INET6 |
| if (th->th_dport == th->th_sport && |
| IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &ip6->ip6_src)) { |
| if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) |
| bsd_log(LOG_DEBUG, "%s; %s: Listen socket: " |
| "Connection attempt to/from self " |
| "ignored\n", s, __func__); |
| goto dropunlock; |
| } |
| if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || |
| IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) { |
| if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) |
| bsd_log(LOG_DEBUG, "%s; %s: Listen socket: " |
| "Connection attempt from/to multicast " |
| "address ignored\n", s, __func__); |
| goto dropunlock; |
| } |
| #endif |
| } else { |
| if (th->th_dport == th->th_sport && |
| ip->ip_dst.s_addr == ip->ip_src.s_addr) { |
| if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) |
| bsd_log(LOG_DEBUG, "%s; %s: Listen socket: " |
| "Connection attempt from/to self " |
| "ignored\n", s, __func__); |
| goto dropunlock; |
| } |
| if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || |
| IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || |
| ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || |
| in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) { |
| if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) |
| bsd_log(LOG_DEBUG, "%s; %s: Listen socket: " |
| "Connection attempt from/to broad- " |
| "or multicast address ignored\n", |
| s, __func__); |
| goto dropunlock; |
| } |
| } |
| /* |
| * SYN appears to be valid. Create compressed TCP state |
| * for syncache. |
| */ |
| #ifdef TCPDEBUG |
| if (so->so_options & SO_DEBUG) |
| tcp_trace(TA_INPUT, ostate, tp, |
| (void *)tcp_saveipgen, &tcp_savetcp, 0); |
| #endif |
| tcp_dooptions(&to, optp, optlen, TO_SYN); |
| syncache_add(&inc, &to, th, inp, &so, m); |
| /* |
| * Entry added to syncache and mbuf consumed. |
| * Everything already unlocked by syncache_add(). |
| */ |
| INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); |
| return; |
| } |
| |
| /* |
| * Segment belongs to a connection in SYN_SENT, ESTABLISHED or later |
| * state. tcp_do_segment() always consumes the mbuf chain, unlocks |
| * the inpcb, and unlocks pcbinfo. |
| */ |
| |
| tcp_do_segment(m, th, so, tp, drop_hdrlen, tlen, iptos, ti_locked); |
| INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); |
| |
| return; |
| |
| dropwithreset: |
| if (ti_locked == TI_RLOCKED) |
| INP_INFO_RUNLOCK(&V_tcbinfo); |
| else if (ti_locked == TI_WLOCKED) |
| INP_INFO_WUNLOCK(&V_tcbinfo); |
| else |
| panic("%s: dropwithreset ti_locked %d", __func__, ti_locked); |
| ti_locked = TI_UNLOCKED; |
| |
| if (inp != NULL) { |
| tcp_dropwithreset(m, th, tp, tlen, rstreason); |
| INP_WUNLOCK(inp); |
| } else |
| tcp_dropwithreset(m, th, NULL, tlen, rstreason); |
| m = NULL; /* mbuf chain got consumed. */ |
| goto drop; |
| |
| dropunlock: |
| if (ti_locked == TI_RLOCKED) |
| INP_INFO_RUNLOCK(&V_tcbinfo); |
| else if (ti_locked == TI_WLOCKED) |
| INP_INFO_WUNLOCK(&V_tcbinfo); |
| else |
| panic("%s: dropunlock ti_locked %d", __func__, ti_locked); |
| ti_locked = TI_UNLOCKED; |
| |
| if (inp != NULL) |
| INP_WUNLOCK(inp); |
| |
| drop: |
| INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); |
| if (s != NULL) |
| bsd_free(s, M_TCPLOG); |
| if (m != NULL) |
| m_freem(m); |
| } |
| |
| static void |
| tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so, |
| struct tcpcb *tp, int drop_hdrlen, int tlen, uint8_t iptos, |
| int ti_locked) |
| { |
| int thflags, acked, ourfinisacked, needoutput = 0; |
| int rstreason, todrop, win; |
| u_long tiwin; |
| struct tcpopt to; |
| |
| #ifdef TCPDEBUG |
| /* |
| * The size of tcp_saveipgen must be the size of the max ip header, |
| * now IPv6. |
| */ |
| u_char tcp_saveipgen[IP6_HDR_LEN]; |
| struct tcphdr tcp_savetcp; |
| short ostate = 0; |
| #endif |
| thflags = th->th_flags; |
| |
| /* |
| * If this is either a state-changing packet or current state isn't |
| * established, we require a write lock on tcbinfo. Otherwise, we |
| * allow either a read lock or a write lock, as we may have acquired |
| * a write lock due to a race. |
| * |
| * Require a global write lock for SYN/FIN/RST segments or |
| * non-established connections; otherwise accept either a read or |
| * write lock, as we may have conservatively acquired a write lock in |
| * certain cases in tcp_input() (is this still true?). Currently we |
| * will never enter with no lock, so we try to drop it quickly in the |
| * common pure ack/pure data cases. |
| */ |
| if ((thflags & (TH_SYN | TH_FIN | TH_RST)) != 0 || |
| tp->t_state != TCPS_ESTABLISHED) { |
| KASSERT(ti_locked == TI_WLOCKED, ("%s ti_locked %d for " |
| "SYN/FIN/RST/!EST", __func__, ti_locked)); |
| INP_INFO_WLOCK_ASSERT(&V_tcbinfo); |
| } else { |
| #ifdef INVARIANTS |
| if (ti_locked == TI_RLOCKED) |
| INP_INFO_RLOCK_ASSERT(&V_tcbinfo); |
| else if (ti_locked == TI_WLOCKED) |
| INP_INFO_WLOCK_ASSERT(&V_tcbinfo); |
| else |
| panic("%s: ti_locked %d for EST", __func__, |
| ti_locked); |
| #endif |
| } |
| INP_WLOCK_ASSERT(tp->t_inpcb); |
| KASSERT(tp->t_state > TCPS_LISTEN, ("%s: TCPS_LISTEN", |
| __func__)); |
| KASSERT(tp->t_state != TCPS_TIME_WAIT, ("%s: TCPS_TIME_WAIT", |
| __func__)); |
| |
| /* |
| * Segment received on connection. |
| * Reset idle time and keep-alive timer. |
| * XXX: This should be done after segment |
| * validation to ignore broken/spoofed segs. |
| */ |
| tp->t_rcvtime = bsd_ticks; |
| if (TCPS_HAVEESTABLISHED(tp->t_state)) |
| tcp_timer_activate(tp, TT_KEEP, tcp_keepidle); |
| |
| /* |
| * Unscale the window into a 32-bit value. |
| * For the SYN_SENT state the scale is zero. |
| */ |
| tiwin = th->th_win << tp->snd_scale; |
| |
| /* |
| * TCP ECN processing. |
| */ |
| if (tp->t_flags & TF_ECN_PERMIT) { |
| switch (iptos & IPTOS_ECN_MASK) { |
| case IPTOS_ECN_CE: |
| tp->t_flags |= TF_ECN_SND_ECE; |
| TCPSTAT_INC(tcps_ecn_ce); |
| break; |
| case IPTOS_ECN_ECT0: |
| TCPSTAT_INC(tcps_ecn_ect0); |
| break; |
| case IPTOS_ECN_ECT1: |
| TCPSTAT_INC(tcps_ecn_ect1); |
| break; |
| } |
| |
| if (thflags & TH_CWR) |
| tp->t_flags &= ~TF_ECN_SND_ECE; |
| |
| /* |
| * Congestion experienced. |
| * Ignore if we are already trying to recover. |
| */ |
| if ((thflags & TH_ECE) && |
| SEQ_LEQ(th->th_ack, tp->snd_recover)) { |
| TCPSTAT_INC(tcps_ecn_rcwnd); |
| tcp_congestion_exp(tp); |
| } |
| } |
| |
| /* |
| * Parse options on any incoming segment. |
| */ |
| tcp_dooptions(&to, (u_char *)(th + 1), |
| (th->th_off << 2) - sizeof(struct tcphdr), |
| (thflags & TH_SYN) ? TO_SYN : 0); |
| |
| /* |
| * If echoed timestamp is later than the current time, |
| * fall back to non RFC1323 RTT calculation. Normalize |
| * timestamp if syncookies were used when this connection |
| * was established. |
| */ |
| if ((to.to_flags & TOF_TS) && (to.to_tsecr != 0)) { |
| to.to_tsecr -= tp->ts_offset; |
| if (TSTMP_GT(to.to_tsecr, bsd_ticks)) |
| to.to_tsecr = 0; |
| } |
| |
| /* |
| * Process options only when we get SYN/ACK back. The SYN case |
| * for incoming connections is handled in tcp_syncache. |
| * According to RFC1323 the window field in a SYN (i.e., a <SYN> |
| * or <SYN,ACK>) segment itself is never scaled. |
| * XXX this is traditional behavior, may need to be cleaned up. |
| */ |
| if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) { |
| if ((to.to_flags & TOF_SCALE) && |
| (tp->t_flags & TF_REQ_SCALE)) { |
| tp->t_flags |= TF_RCVD_SCALE; |
| tp->snd_scale = to.to_wscale; |
| } |
| /* |
| * Initial send window. It will be updated with |
| * the next incoming segment to the scaled value. |
| */ |
| tp->snd_wnd = th->th_win; |
| if (to.to_flags & TOF_TS) { |
| tp->t_flags |= TF_RCVD_TSTMP; |
| tp->ts_recent = to.to_tsval; |
| tp->ts_recent_age = bsd_ticks; |
| } |
| if (to.to_flags & TOF_MSS) |
| tcp_mss(tp, to.to_mss); |
| if ((tp->t_flags & TF_SACK_PERMIT) && |
| (to.to_flags & TOF_SACKPERM) == 0) |
| tp->t_flags &= ~TF_SACK_PERMIT; |
| } |
| |
| /* |
| * Header prediction: check for the two common cases |
| * of a uni-directional data xfer. If the packet has |
| * no control flags, is in-sequence, the window didn't |
| * change and we're not retransmitting, it's a |
| * candidate. If the length is zero and the ack moved |
| * forward, we're the sender side of the xfer. Just |
| * free the data acked & wake any higher level process |
| * that was blocked waiting for space. If the length |
| * is non-zero and the ack didn't move, we're the |
| * receiver side. If we're getting packets in-order |
| * (the reassembly queue is empty), add the data to |
| * the socket buffer and note that we need a delayed ack. |
| * Make sure that the hidden state-flags are also off. |
| * Since we check for TCPS_ESTABLISHED first, it can only |
| * be TH_NEEDSYN. |
| */ |
| if (tp->t_state == TCPS_ESTABLISHED && |
| th->th_seq == tp->rcv_nxt && |
| (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && |
| tp->snd_nxt == tp->snd_max && |
| tiwin && tiwin == tp->snd_wnd && |
| ((tp->t_flags & (TF_NEEDSYN|TF_NEEDFIN)) == 0) && |
| LIST_EMPTY(&tp->t_segq) && |
| ((to.to_flags & TOF_TS) == 0 || |
| TSTMP_GEQ(to.to_tsval, tp->ts_recent)) ) { |
| |
| /* |
| * If last ACK falls within this segment's sequence numbers, |
| * record the timestamp. |
| * NOTE that the test is modified according to the latest |
| * proposal of the tcplw@cray.com list (Braden 1993/04/26). |
| */ |
| if ((to.to_flags & TOF_TS) != 0 && |
| SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { |
| tp->ts_recent_age = bsd_ticks; |
| tp->ts_recent = to.to_tsval; |
| } |
| |
| if (tlen == 0) { |
| if (SEQ_GT(th->th_ack, tp->snd_una) && |
| SEQ_LEQ(th->th_ack, tp->snd_max) && |
| tp->snd_cwnd >= tp->snd_wnd && |
| ((!V_tcp_do_newreno && |
| !(tp->t_flags & TF_SACK_PERMIT) && |
| tp->t_dupacks < tcprexmtthresh) || |
| ((V_tcp_do_newreno || |
| (tp->t_flags & TF_SACK_PERMIT)) && |
| !IN_FASTRECOVERY(tp) && |
| (to.to_flags & TOF_SACK) == 0 && |
| TAILQ_EMPTY(&tp->snd_holes)))) { |
| /* |
| * This is a pure ack for outstanding data. |
| */ |
| if (ti_locked == TI_RLOCKED) |
| INP_INFO_RUNLOCK(&V_tcbinfo); |
| else if (ti_locked == TI_WLOCKED) |
| INP_INFO_WUNLOCK(&V_tcbinfo); |
| else |
| panic("%s: ti_locked %d on pure ACK", |
| __func__, ti_locked); |
| ti_locked = TI_UNLOCKED; |
| |
| TCPSTAT_INC(tcps_predack); |
| |
| /* |
| * "bad retransmit" recovery. |
| */ |
| if (tp->t_rxtshift == 1 && |
| (int)(bsd_ticks - tp->t_badrxtwin) < 0) { |
| TCPSTAT_INC(tcps_sndrexmitbad); |
| tp->snd_cwnd = tp->snd_cwnd_prev; |
| tp->snd_ssthresh = |
| tp->snd_ssthresh_prev; |
| tp->snd_recover = tp->snd_recover_prev; |
| if (tp->t_flags & TF_WASFRECOVERY) |
| ENTER_FASTRECOVERY(tp); |
| tp->snd_nxt = tp->snd_max; |
| tp->t_badrxtwin = 0; |
| } |
| |
| /* |
| * Recalculate the transmit timer / rtt. |
| * |
| * Some boxes send broken timestamp replies |
| * during the SYN+ACK phase, ignore |
| * timestamps of 0 or we could calculate a |
| * huge RTT and blow up the retransmit timer. |
| */ |
| if ((to.to_flags & TOF_TS) != 0 && |
| to.to_tsecr) { |
| if (!tp->t_rttlow || |
| tp->t_rttlow > bsd_ticks - to.to_tsecr) |
| tp->t_rttlow = bsd_ticks - to.to_tsecr; |
| tcp_xmit_timer(tp, |
| bsd_ticks - to.to_tsecr + 1); |
| } else if (tp->t_rtttime && |
| SEQ_GT(th->th_ack, tp->t_rtseq)) { |
| if (!tp->t_rttlow || |
| tp->t_rttlow > bsd_ticks - tp->t_rtttime) |
| tp->t_rttlow = bsd_ticks - tp->t_rtttime; |
| tcp_xmit_timer(tp, |
| bsd_ticks - tp->t_rtttime); |
| } |
| tcp_xmit_bandwidth_limit(tp, th->th_ack); |
| acked = th->th_ack - tp->snd_una; |
| TCPSTAT_INC(tcps_rcvackpack); |
| TCPSTAT_ADD(tcps_rcvackbyte, acked); |
| sbdrop(&so->so_snd, acked); |
| if (SEQ_GT(tp->snd_una, tp->snd_recover) && |
| SEQ_LEQ(th->th_ack, tp->snd_recover)) |
| tp->snd_recover = th->th_ack - 1; |
| tp->snd_una = th->th_ack; |
| /* |
| * Pull snd_wl2 up to prevent seq wrap relative |
| * to th_ack. |
| */ |
| tp->snd_wl2 = th->th_ack; |
| tp->t_dupacks = 0; |
| m_freem(m); |
| ND6_HINT(tp); /* Some progress has been made. */ |
| |
| /* |
| * If all outstanding data are acked, stop |
| * retransmit timer, otherwise restart timer |
| * using current (possibly backed-off) value. |
| * If process is waiting for space, |
| * wakeup/selwakeup/signal. If data |
| * are ready to send, let tcp_output |
| * decide between more output or persist. |
| */ |
| #ifdef TCPDEBUG |
| if (so->so_options & SO_DEBUG) |
| tcp_trace(TA_INPUT, ostate, tp, |
| (void *)tcp_saveipgen, |
| &tcp_savetcp, 0); |
| #endif |
| if (tp->snd_una == tp->snd_max) |
| tcp_timer_activate(tp, TT_REXMT, 0); |
| else if (!tcp_timer_active(tp, TT_PERSIST)) |
| tcp_timer_activate(tp, TT_REXMT, |
| tp->t_rxtcur); |
| sowwakeup(so); |
| if (so->so_snd.sb_cc) |
| (void) tcp_output(tp); |
| goto check_delack; |
| } |
| } else if (th->th_ack == tp->snd_una && |
| tlen <= sbspace(&so->so_rcv)) { |
| int newsize = 0; /* automatic sockbuf scaling */ |
| |
| /* |
| * This is a pure, in-sequence data packet with |
| * nothing on the reassembly queue and we have enough |
| * buffer space to take it. |
| */ |
| if (ti_locked == TI_RLOCKED) |
| INP_INFO_RUNLOCK(&V_tcbinfo); |
| else if (ti_locked == TI_WLOCKED) |
| INP_INFO_WUNLOCK(&V_tcbinfo); |
| else |
| panic("%s: ti_locked %d on pure data " |
| "segment", __func__, ti_locked); |
| ti_locked = TI_UNLOCKED; |
| |
| /* Clean receiver SACK report if present */ |
| if ((tp->t_flags & TF_SACK_PERMIT) && tp->rcv_numsacks) |
| tcp_clean_sackreport(tp); |
| TCPSTAT_INC(tcps_preddat); |
| tp->rcv_nxt += tlen; |
| /* |
| * Pull snd_wl1 up to prevent seq wrap relative to |
| * th_seq. |
| */ |
| tp->snd_wl1 = th->th_seq; |
| /* |
| * Pull rcv_up up to prevent seq wrap relative to |
| * rcv_nxt. |
| */ |
| tp->rcv_up = tp->rcv_nxt; |
| TCPSTAT_INC(tcps_rcvpack); |
| TCPSTAT_ADD(tcps_rcvbyte, tlen); |
| ND6_HINT(tp); /* Some progress has been made */ |
| #ifdef TCPDEBUG |
| if (so->so_options & SO_DEBUG) |
| tcp_trace(TA_INPUT, ostate, tp, |
| (void *)tcp_saveipgen, &tcp_savetcp, 0); |
| #endif |
| /* |
| * Automatic sizing of receive socket buffer. Often the send |
| * buffer size is not optimally adjusted to the actual network |
| * conditions at hand (delay bandwidth product). Setting the |
| * buffer size too small limits throughput on links with high |
| * bandwidth and high delay (eg. trans-continental/oceanic links). |
| * |
| * On the receive side the socket buffer memory is only rarely |
| * used to any significant extent. This allows us to be much |
| * more aggressive in scaling the receive socket buffer. For |
| * the case that the buffer space is actually used to a large |
| * extent and we run out of kernel memory we can simply drop |
| * the new segments; TCP on the sender will just retransmit it |
| * later. Setting the buffer size too big may only consume too |
| * much kernel memory if the application doesn't read() from |
| * the socket or packet loss or reordering makes use of the |
| * reassembly queue. |
| * |
| * The criteria to step up the receive buffer one notch are: |
| * 1. the number of bytes received during the time it takes |
| * one timestamp to be reflected back to us (the RTT); |
| * 2. received bytes per RTT is within seven eighth of the |
| * current socket buffer size; |
| * 3. receive buffer size has not hit maximal automatic size; |
| * |
| * This algorithm does one step per RTT at most and only if |
| * we receive a bulk stream w/o packet losses or reorderings. |
| * Shrinking the buffer during idle times is not necessary as |
| * it doesn't consume any memory when idle. |
| * |
| * TODO: Only step up if the application is actually serving |
| * the buffer to better manage the socket buffer resources. |
| */ |
| if (V_tcp_do_autorcvbuf && |
| to.to_tsecr && |
| (so->so_rcv.sb_flags & SB_AUTOSIZE)) { |
| if (to.to_tsecr > tp->rfbuf_ts && |
| to.to_tsecr - tp->rfbuf_ts < bsd_hz) { |
| if (tp->rfbuf_cnt > |
| (so->so_rcv.sb_hiwat / 8 * 7) && |
| so->so_rcv.sb_hiwat < |
| V_tcp_autorcvbuf_max) { |
| newsize = |
| min(so->so_rcv.sb_hiwat + |
| V_tcp_autorcvbuf_inc, |
| V_tcp_autorcvbuf_max); |
| } |
| /* Start over with next RTT. */ |
| tp->rfbuf_ts = 0; |
| tp->rfbuf_cnt = 0; |
| } else |
| tp->rfbuf_cnt += tlen; /* add up */ |
| } |
| |
| /* Add data to socket buffer. */ |
| SOCKBUF_LOCK(&so->so_rcv); |
| if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { |
| m_freem(m); |
| } else { |
| /* |
| * Set new socket buffer size. |
| * Give up when limit is reached. |
| */ |
| if (newsize) |
| if (!sbreserve_locked(&so->so_rcv, |
| newsize, so, NULL)) |
| so->so_rcv.sb_flags &= ~SB_AUTOSIZE; |
| m_adj(m, drop_hdrlen); /* delayed header drop */ |
| sbappendstream_locked(&so->so_rcv, m); |
| } |
| /* NB: sorwakeup_locked() does an implicit unlock. */ |
| sorwakeup_locked(so); |
| if (DELAY_ACK(tp)) { |
| tp->t_flags |= TF_DELACK; |
| } else { |
| tp->t_flags |= TF_ACKNOW; |
| tcp_output(tp); |
| } |
| |
| goto check_delack; |
| } |
| } |
| |
| /* |
| * Calculate amount of space in receive window, |
| * and then do TCP input processing. |
| * Receive window is amount of space in rcv queue, |
| * but not less than advertised window. |
| */ |
| win = sbspace(&so->so_rcv); |
| if (win < 0) |
| win = 0; |
| tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); |
| |
| /* Reset receive buffer auto scaling when not in bulk receive mode. */ |
| tp->rfbuf_ts = 0; |
| tp->rfbuf_cnt = 0; |
| |
| switch (tp->t_state) { |
| |
| /* |
| * If the state is SYN_RECEIVED: |
| * if seg contains an ACK, but not for our SYN/ACK, send a RST. |
| */ |
| case TCPS_SYN_RECEIVED: |
| if ((thflags & TH_ACK) && |
| (SEQ_LEQ(th->th_ack, tp->snd_una) || |
| SEQ_GT(th->th_ack, tp->snd_max))) { |
| rstreason = BANDLIM_RST_OPENPORT; |
| goto dropwithreset; |
| } |
| break; |
| |
| /* |
| * If the state is SYN_SENT: |
| * if seg contains an ACK, but not for our SYN, drop the input. |
| * if seg contains a RST, then drop the connection. |
| * if seg does not contain SYN, then drop it. |
| * Otherwise this is an acceptable SYN segment |
| * initialize tp->rcv_nxt and tp->irs |
| * if seg contains ack then advance tp->snd_una |
| * if seg contains an ECE and ECN support is enabled, the stream |
| * is ECN capable. |
| * if SYN has been acked change to ESTABLISHED else SYN_RCVD state |
| * arrange for segment to be acked (eventually) |
| * continue processing rest of data/controls, beginning with URG |
| */ |
| case TCPS_SYN_SENT: |
| if ((thflags & TH_ACK) && |
| (SEQ_LEQ(th->th_ack, tp->iss) || |
| SEQ_GT(th->th_ack, tp->snd_max))) { |
| rstreason = BANDLIM_UNLIMITED; |
| goto dropwithreset; |
| } |
| if ((thflags & (TH_ACK|TH_RST)) == (TH_ACK|TH_RST)) |
| tp = tcp_drop(tp, ECONNREFUSED); |
| if (thflags & TH_RST) |
| goto drop; |
| if (!(thflags & TH_SYN)) |
| goto drop; |
| |
| tp->irs = th->th_seq; |
| tcp_rcvseqinit(tp); |
| if (thflags & TH_ACK) { |
| TCPSTAT_INC(tcps_connects); |
| soisconnected(so); |
| #ifdef MAC |
| mac_socketpeer_set_from_mbuf(m, so); |
| #endif |
| /* Do window scaling on this connection? */ |
| if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == |
| (TF_RCVD_SCALE|TF_REQ_SCALE)) { |
| tp->rcv_scale = tp->request_r_scale; |
| } |
| tp->rcv_adv += tp->rcv_wnd; |
| tp->snd_una++; /* SYN is acked */ |
| /* |
| * If there's data, delay ACK; if there's also a FIN |
| * ACKNOW will be turned on later. |
| */ |
| if (DELAY_ACK(tp) && tlen != 0) |
| tcp_timer_activate(tp, TT_DELACK, |
| tcp_delacktime); |
| else |
| tp->t_flags |= TF_ACKNOW; |
| |
| if ((thflags & TH_ECE) && V_tcp_do_ecn) { |
| tp->t_flags |= TF_ECN_PERMIT; |
| TCPSTAT_INC(tcps_ecn_shs); |
| } |
| |
| /* |
| * Received <SYN,ACK> in SYN_SENT[*] state. |
| * Transitions: |
| * SYN_SENT --> ESTABLISHED |
| * SYN_SENT* --> FIN_WAIT_1 |
| */ |
| tp->t_starttime = bsd_ticks; |
| if (tp->t_flags & TF_NEEDFIN) { |
| tp->t_state = TCPS_FIN_WAIT_1; |
| tp->t_flags &= ~TF_NEEDFIN; |
| thflags &= ~TH_SYN; |
| } else { |
| tp->t_state = TCPS_ESTABLISHED; |
| tcp_timer_activate(tp, TT_KEEP, tcp_keepidle); |
| } |
| } else { |
| /* |
| * Received initial SYN in SYN-SENT[*] state => |
| * simultaneous open. If segment contains CC option |
| * and there is a cached CC, apply TAO test. |
| * If it succeeds, connection is * half-synchronized. |
| * Otherwise, do 3-way handshake: |
| * SYN-SENT -> SYN-RECEIVED |
| * SYN-SENT* -> SYN-RECEIVED* |
| * If there was no CC option, clear cached CC value. |
| */ |
| tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN); |
| tcp_timer_activate(tp, TT_REXMT, 0); |
| tp->t_state = TCPS_SYN_RECEIVED; |
| } |
| |
| KASSERT(ti_locked == TI_WLOCKED, ("%s: trimthenstep6: " |
| "ti_locked %d", __func__, ti_locked)); |
| INP_INFO_WLOCK_ASSERT(&V_tcbinfo); |
| INP_WLOCK_ASSERT(tp->t_inpcb); |
| |
| /* |
| * Advance th->th_seq to correspond to first data byte. |
| * If data, trim to stay within window, |
| * dropping FIN if necessary. |
| */ |
| th->th_seq++; |
| if (tlen > tp->rcv_wnd) { |
| todrop = tlen - tp->rcv_wnd; |
| m_adj(m, -todrop); |
| tlen = tp->rcv_wnd; |
| thflags &= ~TH_FIN; |
| TCPSTAT_INC(tcps_rcvpackafterwin); |
| TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); |
| } |
| tp->snd_wl1 = th->th_seq - 1; |
| tp->rcv_up = th->th_seq; |
| /* |
| * Client side of transaction: already sent SYN and data. |
| * If the remote host used T/TCP to validate the SYN, |
| * our data will be ACK'd; if so, enter normal data segment |
| * processing in the middle of step 5, ack processing. |
| * Otherwise, goto step 6. |
| */ |
| if (thflags & TH_ACK) |
| goto process_ACK; |
| |
| goto step6; |
| |
| /* |
| * If the state is LAST_ACK or CLOSING or TIME_WAIT: |
| * do normal processing. |
| * |
| * NB: Leftover from RFC1644 T/TCP. Cases to be reused later. |
| */ |
| case TCPS_LAST_ACK: |
| case TCPS_CLOSING: |
| break; /* continue normal processing */ |
| } |
| |
| /* |
| * States other than LISTEN or SYN_SENT. |
| * First check the RST flag and sequence number since reset segments |
| * are exempt from the timestamp and connection count tests. This |
| * fixes a bug introduced by the Stevens, vol. 2, p. 960 bugfix |
| * below which allowed reset segments in half the sequence space |
| * to fall though and be processed (which gives forged reset |
| * segments with a random sequence number a 50 percent chance of |
| * killing a connection). |
| * Then check timestamp, if present. |
| * Then check the connection count, if present. |
| * Then check that at least some bytes of segment are within |
| * receive window. If segment begins before rcv_nxt, |
| * drop leading data (and SYN); if nothing left, just ack. |
| * |
| * |
| * If the RST bit is set, check the sequence number to see |
| * if this is a valid reset segment. |
| * RFC 793 page 37: |
| * In all states except SYN-SENT, all reset (RST) segments |
| * are validated by checking their SEQ-fields. A reset is |
| * valid if its sequence number is in the window. |
| * Note: this does not take into account delayed ACKs, so |
| * we should test against last_ack_sent instead of rcv_nxt. |
| * The sequence number in the reset segment is normally an |
| * echo of our outgoing acknowlegement numbers, but some hosts |
| * send a reset with the sequence number at the rightmost edge |
| * of our receive window, and we have to handle this case. |
| * Note 2: Paul Watson's paper "Slipping in the Window" has shown |
| * that brute force RST attacks are possible. To combat this, |
| * we use a much stricter check while in the ESTABLISHED state, |
| * only accepting RSTs where the sequence number is equal to |
| * last_ack_sent. In all other states (the states in which a |
| * RST is more likely), the more permissive check is used. |
| * If we have multiple segments in flight, the initial reset |
| * segment sequence numbers will be to the left of last_ack_sent, |
| * but they will eventually catch up. |
| * In any case, it never made sense to trim reset segments to |
| * fit the receive window since RFC 1122 says: |
| * 4.2.2.12 RST Segment: RFC-793 Section 3.4 |
| * |
| * A TCP SHOULD allow a received RST segment to include data. |
| * |
| * DISCUSSION |
| * It has been suggested that a RST segment could contain |
| * ASCII text that encoded and explained the cause of the |
| * RST. No standard has yet been established for such |
| * data. |
| * |
| * If the reset segment passes the sequence number test examine |
| * the state: |
| * SYN_RECEIVED STATE: |
| * If passive open, return to LISTEN state. |
| * If active open, inform user that connection was refused. |
| * ESTABLISHED, FIN_WAIT_1, FIN_WAIT_2, CLOSE_WAIT STATES: |
| * Inform user that connection was reset, and close tcb. |
| * CLOSING, LAST_ACK STATES: |
| * Close the tcb. |
| * TIME_WAIT STATE: |
| * Drop the segment - see Stevens, vol. 2, p. 964 and |
| * RFC 1337. |
| */ |
| if (thflags & TH_RST) { |
| if (SEQ_GEQ(th->th_seq, tp->last_ack_sent - 1) && |
| SEQ_LEQ(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { |
| switch (tp->t_state) { |
| |
| case TCPS_SYN_RECEIVED: |
| so->so_error = ECONNREFUSED; |
| goto close; |
| |
| case TCPS_ESTABLISHED: |
| if (V_tcp_insecure_rst == 0 && |
| !(SEQ_GEQ(th->th_seq, tp->rcv_nxt - 1) && |
| SEQ_LEQ(th->th_seq, tp->rcv_nxt + 1)) && |
| !(SEQ_GEQ(th->th_seq, tp->last_ack_sent - 1) && |
| SEQ_LEQ(th->th_seq, tp->last_ack_sent + 1))) { |
| TCPSTAT_INC(tcps_badrst); |
| goto drop; |
| } |
| /* FALLTHROUGH */ |
| case TCPS_FIN_WAIT_1: |
| case TCPS_FIN_WAIT_2: |
| case TCPS_CLOSE_WAIT: |
| so->so_error = ECONNRESET; |
| close: |
| KASSERT(ti_locked == TI_WLOCKED, |
| ("tcp_do_segment: TH_RST 1 ti_locked %d", |
| ti_locked)); |
| INP_INFO_WLOCK_ASSERT(&V_tcbinfo); |
| |
| tp->t_state = TCPS_CLOSED; |
| TCPSTAT_INC(tcps_drops); |
| tp = tcp_close(tp); |
| break; |
| |
| case TCPS_CLOSING: |
| case TCPS_LAST_ACK: |
| KASSERT(ti_locked == TI_WLOCKED, |
| ("tcp_do_segment: TH_RST 2 ti_locked %d", |
| ti_locked)); |
| INP_INFO_WLOCK_ASSERT(&V_tcbinfo); |
| |
| tp = tcp_close(tp); |
| break; |
| } |
| } |
| goto drop; |
| } |
| |
| /* |
| * RFC 1323 PAWS: If we have a timestamp reply on this segment |
| * and it's less than ts_recent, drop it. |
| */ |
| if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && |
| TSTMP_LT(to.to_tsval, tp->ts_recent)) { |
| |
| /* Check to see if ts_recent is over 24 days old. */ |
| if (bsd_ticks - tp->ts_recent_age > TCP_PAWS_IDLE) { |
| /* |
| * Invalidate ts_recent. If this segment updates |
| * ts_recent, the age will be reset later and ts_recent |
| * will get a valid value. If it does not, setting |
| * ts_recent to zero will at least satisfy the |
| * requirement that zero be placed in the timestamp |
| * echo reply when ts_recent isn't valid. The |
| * age isn't reset until we get a valid ts_recent |
| * because we don't want out-of-order segments to be |
| * dropped when ts_recent is old. |
| */ |
| tp->ts_recent = 0; |
| } else { |
| TCPSTAT_INC(tcps_rcvduppack); |
| TCPSTAT_ADD(tcps_rcvdupbyte, tlen); |
| TCPSTAT_INC(tcps_pawsdrop); |
| if (tlen) |
| goto dropafterack; |
| goto drop; |
| } |
| } |
| |
| /* |
| * In the SYN-RECEIVED state, validate that the packet belongs to |
| * this connection before trimming the data to fit the receive |
| * window. Check the sequence number versus IRS since we know |
| * the sequence numbers haven't wrapped. This is a partial fix |
| * for the "LAND" DoS attack. |
| */ |
| if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) { |
| rstreason = BANDLIM_RST_OPENPORT; |
| goto dropwithreset; |
| } |
| |
| todrop = tp->rcv_nxt - th->th_seq; |
| if (todrop > 0) { |
| /* |
| * If this is a duplicate SYN for our current connection, |
| * advance over it and pretend and it's not a SYN. |
| */ |
| if (thflags & TH_SYN && th->th_seq == tp->irs) { |
| thflags &= ~TH_SYN; |
| th->th_seq++; |
| if (th->th_urp > 1) |
| th->th_urp--; |
| else |
| thflags &= ~TH_URG; |
| todrop--; |
| } |
| /* |
| * Following if statement from Stevens, vol. 2, p. 960. |
| */ |
| if (todrop > tlen |
| || (todrop == tlen && (thflags & TH_FIN) == 0)) { |
| /* |
| * Any valid FIN must be to the left of the window. |
| * At this point the FIN must be a duplicate or out |
| * of sequence; drop it. |
| */ |
| thflags &= ~TH_FIN; |
| |
| /* |
| * Send an ACK to resynchronize and drop any data. |
| * But keep on processing for RST or ACK. |
| */ |
| tp->t_flags |= TF_ACKNOW; |
| todrop = tlen; |
| TCPSTAT_INC(tcps_rcvduppack); |
| TCPSTAT_ADD(tcps_rcvdupbyte, todrop); |
| } else { |
| TCPSTAT_INC(tcps_rcvpartduppack); |
| TCPSTAT_ADD(tcps_rcvpartdupbyte, todrop); |
| } |
| drop_hdrlen += todrop; /* drop from the top afterwards */ |
| th->th_seq += todrop; |
| tlen -= todrop; |
| if (th->th_urp > todrop) |
| th->th_urp -= todrop; |
| else { |
| thflags &= ~TH_URG; |
| th->th_urp = 0; |
| } |
| } |
| |
| /* |
| * If new data are received on a connection after the |
| * user processes are gone, then RST the other end. |
| */ |
| if ((so->so_state & SS_NOFDREF) && |
| tp->t_state > TCPS_CLOSE_WAIT && tlen) { |
| char *s; |
| |
| KASSERT(ti_locked == TI_WLOCKED, ("%s: SS_NOFDEREF && " |
| "CLOSE_WAIT && tlen ti_locked %d", __func__, ti_locked)); |
| INP_INFO_WLOCK_ASSERT(&V_tcbinfo); |
| |
| if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) { |
| bsd_log(LOG_DEBUG, "%s; %s: %s: Received %d bytes of data after socket " |
| "was closed, sending RST and removing tcpcb\n", |
| s, __func__, tcpstates[tp->t_state], tlen); |
| bsd_free(s, M_TCPLOG); |
| } |
| tp = tcp_close(tp); |
| TCPSTAT_INC(tcps_rcvafterclose); |
| rstreason = BANDLIM_UNLIMITED; |
| goto dropwithreset; |
| } |
| |
| /* |
| * If segment ends after window, drop trailing data |
| * (and PUSH and FIN); if nothing left, just ACK. |
| */ |
| todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); |
| if (todrop > 0) { |
| TCPSTAT_INC(tcps_rcvpackafterwin); |
| if (todrop >= tlen) { |
| TCPSTAT_ADD(tcps_rcvbyteafterwin, tlen); |
| /* |
| * If window is closed can only take segments at |
| * window edge, and have to drop data and PUSH from |
| * incoming segments. Continue processing, but |
| * remember to ack. Otherwise, drop segment |
| * and ack. |
| */ |
| if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { |
| tp->t_flags |= TF_ACKNOW; |
| TCPSTAT_INC(tcps_rcvwinprobe); |
| } else |
| goto dropafterack; |
| } else |
| TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); |
| m_adj(m, -todrop); |
| tlen -= todrop; |
| thflags &= ~(TH_PUSH|TH_FIN); |
| } |
| |
| /* |
| * If last ACK falls within this segment's sequence numbers, |
| * record its timestamp. |
| * NOTE: |
| * 1) That the test incorporates suggestions from the latest |
| * proposal of the tcplw@cray.com list (Braden 1993/04/26). |
| * 2) That updating only on newer timestamps interferes with |
| * our earlier PAWS tests, so this check should be solely |
| * predicated on the sequence space of this segment. |
| * 3) That we modify the segment boundary check to be |
| * Last.ACK.Sent <= SEG.SEQ + SEG.Len |
| * instead of RFC1323's |
| * Last.ACK.Sent < SEG.SEQ + SEG.Len, |
| * This modified check allows us to overcome RFC1323's |
| * limitations as described in Stevens TCP/IP Illustrated |
| * Vol. 2 p.869. In such cases, we can still calculate the |
| * RTT correctly when RCV.NXT == Last.ACK.Sent. |
| */ |
| if ((to.to_flags & TOF_TS) != 0 && |
| SEQ_LEQ(th->th_seq, tp->last_ack_sent) && |
| SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + |
| ((thflags & (TH_SYN|TH_FIN)) != 0))) { |
| tp->ts_recent_age = bsd_ticks; |
| tp->ts_recent = to.to_tsval; |
| } |
| |
| /* |
| * If a SYN is in the window, then this is an |
| * error and we send an RST and drop the connection. |
| */ |
| if (thflags & TH_SYN) { |
| KASSERT(ti_locked == TI_WLOCKED, |
| ("tcp_do_segment: TH_SYN ti_locked %d", ti_locked)); |
| INP_INFO_WLOCK_ASSERT(&V_tcbinfo); |
| |
| tp = tcp_drop(tp, ECONNRESET); |
| rstreason = BANDLIM_UNLIMITED; |
| goto drop; |
| } |
| |
| /* |
| * If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN |
| * flag is on (half-synchronized state), then queue data for |
| * later processing; else drop segment and return. |
| */ |
| if ((thflags & TH_ACK) == 0) { |
| if (tp->t_state == TCPS_SYN_RECEIVED || |
| (tp->t_flags & TF_NEEDSYN)) |
| goto step6; |
| else if (tp->t_flags & TF_ACKNOW) |
| goto dropafterack; |
| else |
| goto drop; |
| } |
| |
| /* |
| * Ack processing. |
| */ |
| switch (tp->t_state) { |
| |
| /* |
| * In SYN_RECEIVED state, the ack ACKs our SYN, so enter |
| * ESTABLISHED state and continue processing. |
| * The ACK was checked above. |
| */ |
| case TCPS_SYN_RECEIVED: |
| |
| TCPSTAT_INC(tcps_connects); |
| soisconnected(so); |
| /* Do window scaling? */ |
| if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == |
| (TF_RCVD_SCALE|TF_REQ_SCALE)) { |
| tp->rcv_scale = tp->request_r_scale; |
| tp->snd_wnd = tiwin; |
| } |
| /* |
| * Make transitions: |
| * SYN-RECEIVED -> ESTABLISHED |
| * SYN-RECEIVED* -> FIN-WAIT-1 |
| */ |
| tp->t_starttime = bsd_ticks; |
| if (tp->t_flags & TF_NEEDFIN) { |
| tp->t_state = TCPS_FIN_WAIT_1; |
| tp->t_flags &= ~TF_NEEDFIN; |
| } else { |
| tp->t_state = TCPS_ESTABLISHED; |
| tcp_timer_activate(tp, TT_KEEP, tcp_keepidle); |
| } |
| /* |
| * If segment contains data or ACK, will call tcp_reass() |
| * later; if not, do so now to pass queued data to user. |
| */ |
| if (tlen == 0 && (thflags & TH_FIN) == 0) |
| (void) tcp_reass(tp, (struct tcphdr *)0, 0, |
| (struct mbuf *)0); |
| tp->snd_wl1 = th->th_seq - 1; |
| /* FALLTHROUGH */ |
| |
| /* |
| * In ESTABLISHED state: drop duplicate ACKs; ACK out of range |
| * ACKs. If the ack is in the range |
| * tp->snd_una < th->th_ack <= tp->snd_max |
| * then advance tp->snd_una to th->th_ack and drop |
| * data from the retransmission queue. If this ACK reflects |
| * more up to date window information we update our window information. |
| */ |
| case TCPS_ESTABLISHED: |
| case TCPS_FIN_WAIT_1: |
| case TCPS_FIN_WAIT_2: |
| case TCPS_CLOSE_WAIT: |
| case TCPS_CLOSING: |
| case TCPS_LAST_ACK: |
| if (SEQ_GT(th->th_ack, tp->snd_max)) { |
| TCPSTAT_INC(tcps_rcvacktoomuch); |
| goto dropafterack; |
| } |
| if ((tp->t_flags & TF_SACK_PERMIT) && |
| ((to.to_flags & TOF_SACK) || |
| !TAILQ_EMPTY(&tp->snd_holes))) |
| tcp_sack_doack(tp, &to, th->th_ack); |
| if (SEQ_LEQ(th->th_ack, tp->snd_una)) { |
| if (tlen == 0 && tiwin == tp->snd_wnd) { |
| TCPSTAT_INC(tcps_rcvdupack); |
| /* |
| * If we have outstanding data (other than |
| * a window probe), this is a completely |
| * duplicate ack (ie, window info didn't |
| * change), the ack is the biggest we've |
| * seen and we've seen exactly our rexmt |
| * threshhold of them, assume a packet |
| * has been dropped and retransmit it. |
| * Kludge snd_nxt & the congestion |
| * window so we send only this one |
| * packet. |
| * |
| * We know we're losing at the current |
| * window size so do congestion avoidance |
| * (set ssthresh to half the current window |
| * and pull our congestion window back to |
| * the new ssthresh). |
| * |
| * Dup acks mean that packets have left the |
| * network (they're now cached at the receiver) |
| * so bump cwnd by the amount in the receiver |
| * to keep a constant cwnd packets in the |
| * network. |
| * |
| * When using TCP ECN, notify the peer that |
| * we reduced the cwnd. |
| */ |
| if (!tcp_timer_active(tp, TT_REXMT) || |
| th->th_ack != tp->snd_una) |
| tp->t_dupacks = 0; |
| else if (++tp->t_dupacks > tcprexmtthresh || |
| ((V_tcp_do_newreno || |
| (tp->t_flags & TF_SACK_PERMIT)) && |
| IN_FASTRECOVERY(tp))) { |
| if ((tp->t_flags & TF_SACK_PERMIT) && |
| IN_FASTRECOVERY(tp)) { |
| int awnd; |
| |
| /* |
| * Compute the amount of data in flight first. |
| * We can inject new data into the pipe iff |
| * we have less than 1/2 the original window's |
| * worth of data in flight. |
| */ |
| awnd = (tp->snd_nxt - tp->snd_fack) + |
| tp->sackhint.sack_bytes_rexmit; |
| if (awnd < tp->snd_ssthresh) { |
| tp->snd_cwnd += tp->t_maxseg; |
| if (tp->snd_cwnd > tp->snd_ssthresh) |
| tp->snd_cwnd = tp->snd_ssthresh; |
| } |
| } else |
| tp->snd_cwnd += tp->t_maxseg; |
| (void) tcp_output(tp); |
| goto drop; |
| } else if (tp->t_dupacks == tcprexmtthresh) { |
| tcp_seq onxt = tp->snd_nxt; |
| |
| /* |
| * If we're doing sack, check to |
| * see if we're already in sack |
| * recovery. If we're not doing sack, |
| * check to see if we're in newreno |
| * recovery. |
| */ |
| if (tp->t_flags & TF_SACK_PERMIT) { |
| if (IN_FASTRECOVERY(tp)) { |
| tp->t_dupacks = 0; |
| break; |
| } |
| } else if (V_tcp_do_newreno || |
| V_tcp_do_ecn) { |
| if (SEQ_LEQ(th->th_ack, |
| tp->snd_recover)) { |
| tp->t_dupacks = 0; |
| break; |
| } |
| } |
| tcp_congestion_exp(tp); |
| tcp_timer_activate(tp, TT_REXMT, 0); |
| tp->t_rtttime = 0; |
| if (tp->t_flags & TF_SACK_PERMIT) { |
| TCPSTAT_INC( |
| tcps_sack_recovery_episode); |
| tp->sack_newdata = tp->snd_nxt; |
| tp->snd_cwnd = tp->t_maxseg; |
| (void) tcp_output(tp); |
| goto drop; |
| } |
| tp->snd_nxt = th->th_ack; |
| tp->snd_cwnd = tp->t_maxseg; |
| (void) tcp_output(tp); |
| KASSERT(tp->snd_limited <= 2, |
| ("%s: tp->snd_limited too big", |
| __func__)); |
| tp->snd_cwnd = tp->snd_ssthresh + |
| tp->t_maxseg * |
| (tp->t_dupacks - tp->snd_limited); |
| if (SEQ_GT(onxt, tp->snd_nxt)) |
| tp->snd_nxt = onxt; |
| goto drop; |
| } else if (V_tcp_do_rfc3042) { |
| u_long oldcwnd = tp->snd_cwnd; |
| tcp_seq oldsndmax = tp->snd_max; |
| u_int sent; |
| |
| KASSERT(tp->t_dupacks == 1 || |
| tp->t_dupacks == 2, |
| ("%s: dupacks not 1 or 2", |
| __func__)); |
| if (tp->t_dupacks == 1) |
| tp->snd_limited = 0; |
| tp->snd_cwnd = |
| (tp->snd_nxt - tp->snd_una) + |
| (tp->t_dupacks - tp->snd_limited) * |
| tp->t_maxseg; |
| (void) tcp_output(tp); |
| sent = tp->snd_max - oldsndmax; |
| if (sent > tp->t_maxseg) { |
| KASSERT((tp->t_dupacks == 2 && |
| tp->snd_limited == 0) || |
| (sent == tp->t_maxseg + 1 && |
| tp->t_flags & TF_SENTFIN), |
| ("%s: sent too much", |
| __func__)); |
| tp->snd_limited = 2; |
| } else if (sent > 0) |
| ++tp->snd_limited; |
| tp->snd_cwnd = oldcwnd; |
| goto drop; |
| } |
| } else |
| tp->t_dupacks = 0; |
| break; |
| } |
| |
| KASSERT(SEQ_GT(th->th_ack, tp->snd_una), |
| ("%s: th_ack <= snd_una", __func__)); |
| |
| /* |
| * If the congestion window was inflated to account |
| * for the other side's cached packets, retract it. |
| */ |
| if (V_tcp_do_newreno || (tp->t_flags & TF_SACK_PERMIT)) { |
| if (IN_FASTRECOVERY(tp)) { |
| if (SEQ_LT(th->th_ack, tp->snd_recover)) { |
| if (tp->t_flags & TF_SACK_PERMIT) |
| tcp_sack_partialack(tp, th); |
| else |
| tcp_newreno_partial_ack(tp, th); |
| } else { |
| /* |
| * Out of fast recovery. |
| * Window inflation should have left us |
| * with approximately snd_ssthresh |
| * outstanding data. |
| * But in case we would be inclined to |
| * send a burst, better to do it via |
| * the slow start mechanism. |
| */ |
| if (SEQ_GT(th->th_ack + |
| tp->snd_ssthresh, |
| tp->snd_max)) |
| tp->snd_cwnd = tp->snd_max - |
| th->th_ack + |
| tp->t_maxseg; |
| else |
| tp->snd_cwnd = tp->snd_ssthresh; |
| } |
| } |
| } else { |
| if (tp->t_dupacks >= tcprexmtthresh && |
| tp->snd_cwnd > tp->snd_ssthresh) |
| tp->snd_cwnd = tp->snd_ssthresh; |
| } |
| tp->t_dupacks = 0; |
| /* |
| * If we reach this point, ACK is not a duplicate, |
| * i.e., it ACKs something we sent. |
| */ |
| if (tp->t_flags & TF_NEEDSYN) { |
| /* |
| * T/TCP: Connection was half-synchronized, and our |
| * SYN has been ACK'd (so connection is now fully |
| * synchronized). Go to non-starred state, |
| * increment snd_una for ACK of SYN, and check if |
| * we can do window scaling. |
| */ |
| tp->t_flags &= ~TF_NEEDSYN; |
| tp->snd_una++; |
| /* Do window scaling? */ |
| if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == |
| (TF_RCVD_SCALE|TF_REQ_SCALE)) { |
| tp->rcv_scale = tp->request_r_scale; |
| /* Send window already scaled. */ |
| } |
| } |
| |
| process_ACK: |
| INP_INFO_LOCK_ASSERT(&V_tcbinfo); |
| KASSERT(ti_locked == TI_RLOCKED || ti_locked == TI_WLOCKED, |
| ("tcp_input: process_ACK ti_locked %d", ti_locked)); |
| INP_WLOCK_ASSERT(tp->t_inpcb); |
| |
| acked = th->th_ack - tp->snd_una; |
| TCPSTAT_INC(tcps_rcvackpack); |
| TCPSTAT_ADD(tcps_rcvackbyte, acked); |
| |
| /* |
| * If we just performed our first retransmit, and the ACK |
| * arrives within our recovery window, then it was a mistake |
| * to do the retransmit in the first place. Recover our |
| * original cwnd and ssthresh, and proceed to transmit where |
| * we left off. |
| */ |
| if (tp->t_rxtshift == 1 && (int)(bsd_ticks - tp->t_badrxtwin) < 0) { |
| TCPSTAT_INC(tcps_sndrexmitbad); |
| tp->snd_cwnd = tp->snd_cwnd_prev; |
| tp->snd_ssthresh = tp->snd_ssthresh_prev; |
| tp->snd_recover = tp->snd_recover_prev; |
| if (tp->t_flags & TF_WASFRECOVERY) |
| ENTER_FASTRECOVERY(tp); |
| tp->snd_nxt = tp->snd_max; |
| tp->t_badrxtwin = 0; /* XXX probably not required */ |
| } |
| |
| /* |
| * If we have a timestamp reply, update smoothed |
| * round trip time. If no timestamp is present but |
| * transmit timer is running and timed sequence |
| * number was acked, update smoothed round trip time. |
| * Since we now have an rtt measurement, cancel the |
| * timer backoff (cf., Phil Karn's retransmit alg.). |
| * Recompute the initial retransmit timer. |
| * |
| * Some boxes send broken timestamp replies |
| * during the SYN+ACK phase, ignore |
| * timestamps of 0 or we could calculate a |
| * huge RTT and blow up the retransmit timer. |
| */ |
| if ((to.to_flags & TOF_TS) != 0 && |
| to.to_tsecr) { |
| if (!tp->t_rttlow || tp->t_rttlow > bsd_ticks - to.to_tsecr) |
| tp->t_rttlow = bsd_ticks - to.to_tsecr; |
| tcp_xmit_timer(tp, bsd_ticks - to.to_tsecr + 1); |
| } else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) { |
| if (!tp->t_rttlow || tp->t_rttlow > bsd_ticks - tp->t_rtttime) |
| tp->t_rttlow = bsd_ticks - tp->t_rtttime; |
| tcp_xmit_timer(tp, bsd_ticks - tp->t_rtttime); |
| } |
| tcp_xmit_bandwidth_limit(tp, th->th_ack); |
| |
| /* |
| * If all outstanding data is acked, stop retransmit |
| * timer and remember to restart (more output or persist). |
| * If there is more data to be acked, restart retransmit |
| * timer, using current (possibly backed-off) value. |
| */ |
| if (th->th_ack == tp->snd_max) { |
| tcp_timer_activate(tp, TT_REXMT, 0); |
| needoutput = 1; |
| } else if (!tcp_timer_active(tp, TT_PERSIST)) |
| tcp_timer_activate(tp, TT_REXMT, tp->t_rxtcur); |
| |
| /* |
| * If no data (only SYN) was ACK'd, |
| * skip rest of ACK processing. |
| */ |
| if (acked == 0) |
| goto step6; |
| |
| /* |
| * When new data is acked, open the congestion window. |
| * Method depends on which congestion control state we're |
| * in (slow start or cong avoid) and if ABC (RFC 3465) is |
| * enabled. |
| * |
| * slow start: cwnd <= ssthresh |
| * cong avoid: cwnd > ssthresh |
| * |
| * slow start and ABC (RFC 3465): |
| * Grow cwnd exponentially by the amount of data |
| * ACKed capping the max increment per ACK to |
| * (abc_l_var * maxseg) bytes. |
| * |
| * slow start without ABC (RFC 2581): |
| * Grow cwnd exponentially by maxseg per ACK. |
| * |
| * cong avoid and ABC (RFC 3465): |
| * Grow cwnd linearly by maxseg per RTT for each |
| * cwnd worth of ACKed data. |
| * |
| * cong avoid without ABC (RFC 2581): |
| * Grow cwnd linearly by approximately maxseg per RTT using |
| * maxseg^2 / cwnd per ACK as the increment. |
| * If cwnd > maxseg^2, fix the cwnd increment at 1 byte to |
| * avoid capping cwnd. |
| */ |
| if ((!V_tcp_do_newreno && !(tp->t_flags & TF_SACK_PERMIT)) || |
| !IN_FASTRECOVERY(tp)) { |
| u_int cw = tp->snd_cwnd; |
| u_int incr = tp->t_maxseg; |
| /* In congestion avoidance? */ |
| if (cw > tp->snd_ssthresh) { |
| if (V_tcp_do_rfc3465) { |
| tp->t_bytes_acked += acked; |
| if (tp->t_bytes_acked >= tp->snd_cwnd) |
| tp->t_bytes_acked -= cw; |
| else |
| incr = 0; |
| } |
| else |
| incr = max((incr * incr / cw), 1); |
| /* |
| * In slow-start with ABC enabled and no RTO in sight? |
| * (Must not use abc_l_var > 1 if slow starting after an |
| * RTO. On RTO, snd_nxt = snd_una, so the snd_nxt == |
| * snd_max check is sufficient to handle this). |
| */ |
| } else if (V_tcp_do_rfc3465 && |
| tp->snd_nxt == tp->snd_max) |
| incr = min(acked, |
| V_tcp_abc_l_var * tp->t_maxseg); |
| /* ABC is on by default, so (incr == 0) frequently. */ |
| if (incr > 0) |
| tp->snd_cwnd = min(cw+incr, TCP_MAXWIN<<tp->snd_scale); |
| } |
| SOCKBUF_LOCK(&so->so_snd); |
| if (acked > so->so_snd.sb_cc) { |
| tp->snd_wnd -= so->so_snd.sb_cc; |
| sbdrop_locked(&so->so_snd, (int)so->so_snd.sb_cc); |
| ourfinisacked = 1; |
| } else { |
| sbdrop_locked(&so->so_snd, acked); |
| tp->snd_wnd -= acked; |
| ourfinisacked = 0; |
| } |
| /* NB: sowwakeup_locked() does an implicit unlock. */ |
| sowwakeup_locked(so); |
| /* Detect una wraparound. */ |
| if ((V_tcp_do_newreno || (tp->t_flags & TF_SACK_PERMIT)) && |
| !IN_FASTRECOVERY(tp) && |
| SEQ_GT(tp->snd_una, tp->snd_recover) && |
| SEQ_LEQ(th->th_ack, tp->snd_recover)) |
| tp->snd_recover = th->th_ack - 1; |
| if ((V_tcp_do_newreno || (tp->t_flags & TF_SACK_PERMIT)) && |
| IN_FASTRECOVERY(tp) && |
| SEQ_GEQ(th->th_ack, tp->snd_recover)) { |
| EXIT_FASTRECOVERY(tp); |
| tp->t_bytes_acked = 0; |
| } |
| tp->snd_una = th->th_ack; |
| if (tp->t_flags & TF_SACK_PERMIT) { |
| if (SEQ_GT(tp->snd_una, tp->snd_recover)) |
| tp->snd_recover = tp->snd_una; |
| } |
| if (SEQ_LT(tp->snd_nxt, tp->snd_una)) |
| tp->snd_nxt = tp->snd_una; |
| |
| switch (tp->t_state) { |
| |
| /* |
| * In FIN_WAIT_1 STATE in addition to the processing |
| * for the ESTABLISHED state if our FIN is now acknowledged |
| * then enter FIN_WAIT_2. |
| */ |
| case TCPS_FIN_WAIT_1: |
| if (ourfinisacked) { |
| /* |
| * If we can't receive any more |
| * data, then closing user can proceed. |
| * Starting the timer is contrary to the |
| * specification, but if we don't get a FIN |
| * we'll hang forever. |
| * |
| * XXXjl: |
| * we should release the tp also, and use a |
| * compressed state. |
| */ |
| if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { |
| int timeout; |
| |
| soisdisconnected(so); |
| timeout = (tcp_fast_finwait2_recycle) ? |
| tcp_finwait2_timeout : tcp_maxidle; |
| tcp_timer_activate(tp, TT_2MSL, timeout); |
| } |
| tp->t_state = TCPS_FIN_WAIT_2; |
| } |
| break; |
| |
| /* |
| * In CLOSING STATE in addition to the processing for |
| * the ESTABLISHED state if the ACK acknowledges our FIN |
| * then enter the TIME-WAIT state, otherwise ignore |
| * the segment. |
| */ |
| case TCPS_CLOSING: |
| if (ourfinisacked) { |
| INP_INFO_WLOCK_ASSERT(&V_tcbinfo); |
| tcp_twstart(tp); |
| INP_INFO_WUNLOCK(&V_tcbinfo); |
| m_freem(m); |
| return; |
| } |
| break; |
| |
| /* |
| * In LAST_ACK, we may still be waiting for data to drain |
| * and/or to be acked, as well as for the ack of our FIN. |
| * If our FIN is now acknowledged, delete the TCB, |
| * enter the closed state and return. |
| */ |
| case TCPS_LAST_ACK: |
| if (ourfinisacked) { |
| INP_INFO_WLOCK_ASSERT(&V_tcbinfo); |
| tp = tcp_close(tp); |
| goto drop; |
| } |
| break; |
| } |
| } |
| |
| step6: |
| INP_INFO_LOCK_ASSERT(&V_tcbinfo); |
| KASSERT(ti_locked == TI_RLOCKED || ti_locked == TI_WLOCKED, |
| ("tcp_do_segment: step6 ti_locked %d", ti_locked)); |
| INP_WLOCK_ASSERT(tp->t_inpcb); |
| |
| /* |
| * Update window information. |
| * Don't look at window if no ACK: TAC's send garbage on first SYN. |
| */ |
| if ((thflags & TH_ACK) && |
| (SEQ_LT(tp->snd_wl1, th->th_seq) || |
| (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || |
| (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { |
| /* keep track of pure window updates */ |
| if (tlen == 0 && |
| tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) |
| TCPSTAT_INC(tcps_rcvwinupd); |
| tp->snd_wnd = tiwin; |
| tp->snd_wl1 = th->th_seq; |
| tp->snd_wl2 = th->th_ack; |
| if (tp->snd_wnd > tp->max_sndwnd) |
| tp->max_sndwnd = tp->snd_wnd; |
| needoutput = 1; |
| } |
| |
| /* |
| * Process segments with URG. |
| */ |
| if ((thflags & TH_URG) && th->th_urp && |
| TCPS_HAVERCVDFIN(tp->t_state) == 0) { |
| /* |
| * This is a kludge, but if we receive and accept |
| * random urgent pointers, we'll crash in |
| * soreceive. It's hard to imagine someone |
| * actually wanting to send this much urgent data. |
| */ |
| SOCKBUF_LOCK(&so->so_rcv); |
| if (th->th_urp + so->so_rcv.sb_cc > sb_max) { |
| th->th_urp = 0; /* XXX */ |
| thflags &= ~TH_URG; /* XXX */ |
| SOCKBUF_UNLOCK(&so->so_rcv); /* XXX */ |
| goto dodata; /* XXX */ |
| } |
| /* |
| * If this segment advances the known urgent pointer, |
| * then mark the data stream. This should not happen |
| * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since |
| * a FIN has been received from the remote side. |
| * In these states we ignore the URG. |
| * |
| * According to RFC961 (Assigned Protocols), |
| * the urgent pointer points to the last octet |
| * of urgent data. We continue, however, |
| * to consider it to indicate the first octet |
| * of data past the urgent section as the original |
| * spec states (in one of two places). |
| */ |
| if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { |
| tp->rcv_up = th->th_seq + th->th_urp; |
| so->so_oobmark = so->so_rcv.sb_cc + |
| (tp->rcv_up - tp->rcv_nxt) - 1; |
| if (so->so_oobmark == 0) |
| so->so_rcv.sb_state |= SBS_RCVATMARK; |
| sohasoutofband(so); |
| tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); |
| } |
| SOCKBUF_UNLOCK(&so->so_rcv); |
| /* |
| * Remove out of band data so doesn't get presented to user. |
| * This can happen independent of advancing the URG pointer, |
| * but if two URG's are pending at once, some out-of-band |
| * data may creep in... ick. |
| */ |
| if (th->th_urp <= (u_long)tlen && |
| !(so->so_options & SO_OOBINLINE)) { |
| /* hdr drop is delayed */ |
| tcp_pulloutofband(so, th, m, drop_hdrlen); |
| } |
| } else { |
| /* |
| * If no out of band data is expected, |
| * pull receive urgent pointer along |
| * with the receive window. |
| */ |
| if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) |
| tp->rcv_up = tp->rcv_nxt; |
| } |
| dodata: /* XXX */ |
| INP_INFO_LOCK_ASSERT(&V_tcbinfo); |
| KASSERT(ti_locked == TI_RLOCKED || ti_locked == TI_WLOCKED, |
| ("tcp_do_segment: dodata ti_locked %d", ti_locked)); |
| INP_WLOCK_ASSERT(tp->t_inpcb); |
| |
| /* |
| * Process the segment text, merging it into the TCP sequencing queue, |
| * and arranging for acknowledgment of receipt if necessary. |
| * This process logically involves adjusting tp->rcv_wnd as data |
| * is presented to the user (this happens in tcp_usrreq.c, |
| * case PRU_RCVD). If a FIN has already been received on this |
| * connection then we just ignore the text. |
| */ |
| if ((tlen || (thflags & TH_FIN)) && |
| TCPS_HAVERCVDFIN(tp->t_state) == 0) { |
| tcp_seq save_start = th->th_seq; |
| m_adj(m, drop_hdrlen); /* delayed header drop */ |
| /* |
| * Insert segment which includes th into TCP reassembly queue |
| * with control block tp. Set thflags to whether reassembly now |
| * includes a segment with FIN. This handles the common case |
| * inline (segment is the next to be received on an established |
| * connection, and the queue is empty), avoiding linkage into |
| * and removal from the queue and repetition of various |
| * conversions. |
| * Set DELACK for segments received in order, but ack |
| * immediately when segments are out of order (so |
| * fast retransmit can work). |
| */ |
| if (th->th_seq == tp->rcv_nxt && |
| LIST_EMPTY(&tp->t_segq) && |
| TCPS_HAVEESTABLISHED(tp->t_state)) { |
| if (DELAY_ACK(tp)) |
| tp->t_flags |= TF_DELACK; |
| else |
| tp->t_flags |= TF_ACKNOW; |
| tp->rcv_nxt += tlen; |
| thflags = th->th_flags & TH_FIN; |
| TCPSTAT_INC(tcps_rcvpack); |
| TCPSTAT_ADD(tcps_rcvbyte, tlen); |
| ND6_HINT(tp); |
| SOCKBUF_LOCK(&so->so_rcv); |
| if (so->so_rcv.sb_state & SBS_CANTRCVMORE) |
| m_freem(m); |
| else |
| sbappendstream_locked(&so->so_rcv, m); |
| /* NB: sorwakeup_locked() does an implicit unlock. */ |
| sorwakeup_locked(so); |
| } else { |
| /* |
| * XXX: Due to the header drop above "th" is |
| * theoretically invalid by now. Fortunately |
| * m_adj() doesn't actually frees any mbufs |
| * when trimming from the head. |
| */ |
| thflags = tcp_reass(tp, th, &tlen, m); |
| tp->t_flags |= TF_ACKNOW; |
| } |
| if (tlen > 0 && (tp->t_flags & TF_SACK_PERMIT)) |
| tcp_update_sack_list(tp, save_start, save_start + tlen); |
| #if 0 |
| /* |
| * Note the amount of data that peer has sent into |
| * our window, in order to estimate the sender's |
| * buffer size. |
| * XXX: Unused. |
| */ |
| len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); |
| #endif |
| } else { |
| m_freem(m); |
| thflags &= ~TH_FIN; |
| } |
| |
| /* |
| * If FIN is received ACK the FIN and let the user know |
| * that the connection is closing. |
| */ |
| if (thflags & TH_FIN) { |
| if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { |
| socantrcvmore(so); |
| /* |
| * If connection is half-synchronized |
| * (ie NEEDSYN flag on) then delay ACK, |
| * so it may be piggybacked when SYN is sent. |
| * Otherwise, since we received a FIN then no |
| * more input can be expected, send ACK now. |
| */ |
| if (tp->t_flags & TF_NEEDSYN) |
| tp->t_flags |= TF_DELACK; |
| else |
| tp->t_flags |= TF_ACKNOW; |
| tp->rcv_nxt++; |
| } |
| switch (tp->t_state) { |
| |
| /* |
| * In SYN_RECEIVED and ESTABLISHED STATES |
| * enter the CLOSE_WAIT state. |
| */ |
| case TCPS_SYN_RECEIVED: |
| tp->t_starttime = bsd_ticks; |
| /* FALLTHROUGH */ |
| case TCPS_ESTABLISHED: |
| tp->t_state = TCPS_CLOSE_WAIT; |
| break; |
| |
| /* |
| * If still in FIN_WAIT_1 STATE FIN has not been acked so |
| * enter the CLOSING state. |
| */ |
| case TCPS_FIN_WAIT_1: |
| tp->t_state = TCPS_CLOSING; |
| break; |
| |
| /* |
| * In FIN_WAIT_2 state enter the TIME_WAIT state, |
| * starting the time-wait timer, turning off the other |
| * standard timers. |
| */ |
| case TCPS_FIN_WAIT_2: |
| INP_INFO_WLOCK_ASSERT(&V_tcbinfo); |
| KASSERT(ti_locked == TI_WLOCKED, ("%s: dodata " |
| "TCP_FIN_WAIT_2 ti_locked: %d", __func__, |
| ti_locked)); |
| |
| tcp_twstart(tp); |
| INP_INFO_WUNLOCK(&V_tcbinfo); |
| return; |
| } |
| } |
| if (ti_locked == TI_RLOCKED) |
| INP_INFO_RUNLOCK(&V_tcbinfo); |
| else if (ti_locked == TI_WLOCKED) |
| INP_INFO_WUNLOCK(&V_tcbinfo); |
| else |
| panic("%s: dodata epilogue ti_locked %d", __func__, |
| ti_locked); |
| ti_locked = TI_UNLOCKED; |
| |
| #ifdef TCPDEBUG |
| if (so->so_options & SO_DEBUG) |
| tcp_trace(TA_INPUT, ostate, tp, (void *)tcp_saveipgen, |
| &tcp_savetcp, 0); |
| #endif |
| |
| /* |
| * Return any desired output. |
| */ |
| if (needoutput || (tp->t_flags & TF_ACKNOW)) |
| (void) tcp_output(tp); |
| |
| check_delack: |
| KASSERT(ti_locked == TI_UNLOCKED, ("%s: check_delack ti_locked %d", |
| __func__, ti_locked)); |
| INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); |
| INP_WLOCK_ASSERT(tp->t_inpcb); |
| |
| if (tp->t_flags & TF_DELACK) { |
| tp->t_flags &= ~TF_DELACK; |
| tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); |
| } |
| INP_WUNLOCK(tp->t_inpcb); |
| return; |
| |
| dropafterack: |
| KASSERT(ti_locked == TI_RLOCKED || ti_locked == TI_WLOCKED, |
| ("tcp_do_segment: dropafterack ti_locked %d", ti_locked)); |
| |
| /* |
| * Generate an ACK dropping incoming segment if it occupies |
| * sequence space, where the ACK reflects our state. |
| * |
| * We can now skip the test for the RST flag since all |
| * paths to this code happen after packets containing |
| * RST have been dropped. |
| * |
| * In the SYN-RECEIVED state, don't send an ACK unless the |
| * segment we received passes the SYN-RECEIVED ACK test. |
| * If it fails send a RST. This breaks the loop in the |
| * "LAND" DoS attack, and also prevents an ACK storm |
| * between two listening ports that have been sent forged |
| * SYN segments, each with the source address of the other. |
| */ |
| if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) && |
| (SEQ_GT(tp->snd_una, th->th_ack) || |
| SEQ_GT(th->th_ack, tp->snd_max)) ) { |
| rstreason = BANDLIM_RST_OPENPORT; |
| goto dropwithreset; |
| } |
| #ifdef TCPDEBUG |
| if (so->so_options & SO_DEBUG) |
| tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen, |
| &tcp_savetcp, 0); |
| #endif |
| if (ti_locked == TI_RLOCKED) |
| INP_INFO_RUNLOCK(&V_tcbinfo); |
| else if (ti_locked == TI_WLOCKED) |
| INP_INFO_WUNLOCK(&V_tcbinfo); |
| else |
| panic("%s: dropafterack epilogue ti_locked %d", __func__, |
| ti_locked); |
| ti_locked = TI_UNLOCKED; |
| |
| tp->t_flags |= TF_ACKNOW; |
| (void) tcp_output(tp); |
| INP_WUNLOCK(tp->t_inpcb); |
| m_freem(m); |
| return; |
| |
| dropwithreset: |
| if (ti_locked == TI_RLOCKED) |
| INP_INFO_RUNLOCK(&V_tcbinfo); |
| else if (ti_locked == TI_WLOCKED) |
| INP_INFO_WUNLOCK(&V_tcbinfo); |
| else |
| panic("%s: dropwithreset ti_locked %d", __func__, ti_locked); |
| ti_locked = TI_UNLOCKED; |
| |
| if (tp != NULL) { |
| tcp_dropwithreset(m, th, tp, tlen, rstreason); |
| INP_WUNLOCK(tp->t_inpcb); |
| } else |
| tcp_dropwithreset(m, th, NULL, tlen, rstreason); |
| return; |
| |
| drop: |
| if (ti_locked == TI_RLOCKED) |
| INP_INFO_RUNLOCK(&V_tcbinfo); |
| else if (ti_locked == TI_WLOCKED) |
| INP_INFO_WUNLOCK(&V_tcbinfo); |
| #ifdef INVARIANTS |
| else |
| INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); |
| #endif |
| ti_locked = TI_UNLOCKED; |
| |
| /* |
| * Drop space held by incoming segment and return. |
| */ |
| #ifdef TCPDEBUG |
| if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) |
| tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen, |
| &tcp_savetcp, 0); |
| #endif |
| if (tp != NULL) |
| INP_WUNLOCK(tp->t_inpcb); |
| m_freem(m); |
| } |
| |
| /* |
| * Issue RST and make ACK acceptable to originator of segment. |
| * The mbuf must still include the original packet header. |
| * tp may be NULL. |
| */ |
| static void |
| tcp_dropwithreset(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, |
| int tlen, int rstreason) |
| { |
| struct ip *ip; |
| #ifdef INET6 |
| struct ip6_hdr *ip6; |
| #endif |
| |
| if (tp != NULL) { |
| INP_WLOCK_ASSERT(tp->t_inpcb); |
| } |
| |
| /* Don't bother if destination was broadcast/multicast. */ |
| if ((th->th_flags & TH_RST) || m->m_flags & (M_BCAST|M_MCAST)) |
| goto drop; |
| #ifdef INET6 |
| if (mtod(m, struct ip *)->ip_v == 6) { |
| ip6 = mtod(m, struct ip6_hdr *); |
| if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || |
| IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) |
| goto drop; |
| /* IPv6 anycast check is done at tcp6_input() */ |
| } else |
| #endif |
| { |
| ip = mtod(m, struct ip *); |
| if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || |
| IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || |
| ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || |
| in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) |
| goto drop; |
| } |
| |
| /* Perform bandwidth limiting. */ |
| if (badport_bandlim(rstreason) < 0) |
| goto drop; |
| |
| /* tcp_respond consumes the mbuf chain. */ |
| if (th->th_flags & TH_ACK) { |
| tcp_respond(tp, mtod(m, void *), th, m, (tcp_seq)0, |
| th->th_ack, TH_RST); |
| } else { |
| if (th->th_flags & TH_SYN) |
| tlen++; |
| tcp_respond(tp, mtod(m, void *), th, m, th->th_seq+tlen, |
| (tcp_seq)0, TH_RST|TH_ACK); |
| } |
| return; |
| drop: |
| m_freem(m); |
| } |
| |
| /* |
| * Parse TCP options and place in tcpopt. |
| */ |
| static void |
| tcp_dooptions(struct tcpopt *to, u_char *cp, int cnt, int flags) |
| { |
| int opt, optlen; |
| |
| to->to_flags = 0; |
| for (; cnt > 0; cnt -= optlen, cp += optlen) { |
| opt = cp[0]; |
| if (opt == TCPOPT_EOL) |
| break; |
| if (opt == TCPOPT_NOP) |
| optlen = 1; |
| else { |
| if (cnt < 2) |
| break; |
| optlen = cp[1]; |
| if (optlen < 2 || optlen > cnt) |
| break; |
| } |
| switch (opt) { |
| case TCPOPT_MAXSEG: |
| if (optlen != TCPOLEN_MAXSEG) |
| continue; |
| if (!(flags & TO_SYN)) |
| continue; |
| to->to_flags |= TOF_MSS; |
| bcopy((char *)cp + 2, |
| (char *)&to->to_mss, sizeof(to->to_mss)); |
| to->to_mss = ntohs(to->to_mss); |
| break; |
| case TCPOPT_WINDOW: |
| if (optlen != TCPOLEN_WINDOW) |
| continue; |
| if (!(flags & TO_SYN)) |
| continue; |
| to->to_flags |= TOF_SCALE; |
| to->to_wscale = min(cp[2], TCP_MAX_WINSHIFT); |
| break; |
| case TCPOPT_TIMESTAMP: |
| if (optlen != TCPOLEN_TIMESTAMP) |
| continue; |
| to->to_flags |= TOF_TS; |
| bcopy((char *)cp + 2, |
| (char *)&to->to_tsval, sizeof(to->to_tsval)); |
| to->to_tsval = ntohl(to->to_tsval); |
| bcopy((char *)cp + 6, |
| (char *)&to->to_tsecr, sizeof(to->to_tsecr)); |
| to->to_tsecr = ntohl(to->to_tsecr); |
| break; |
| #ifdef TCP_SIGNATURE |
| /* |
| * XXX In order to reply to a host which has set the |
| * TCP_SIGNATURE option in its initial SYN, we have to |
| * record the fact that the option was observed here |
| * for the syncache code to perform the correct response. |
| */ |
| case TCPOPT_SIGNATURE: |
| if (optlen != TCPOLEN_SIGNATURE) |
| continue; |
| to->to_flags |= TOF_SIGNATURE; |
| to->to_signature = cp + 2; |
| break; |
| #endif |
| case TCPOPT_SACK_PERMITTED: |
| if (optlen != TCPOLEN_SACK_PERMITTED) |
| continue; |
| if (!(flags & TO_SYN)) |
| continue; |
| if (!V_tcp_do_sack) |
| continue; |
| to->to_flags |= TOF_SACKPERM; |
| break; |
| case TCPOPT_SACK: |
| if (optlen <= 2 || (optlen - 2) % TCPOLEN_SACK != 0) |
| continue; |
| if (flags & TO_SYN) |
| continue; |
| to->to_flags |= TOF_SACK; |
| to->to_nsacks = (optlen - 2) / TCPOLEN_SACK; |
| to->to_sacks = cp + 2; |
| TCPSTAT_INC(tcps_sack_rcv_blocks); |
| break; |
| default: |
| continue; |
| } |
| } |
| } |
| |
| /* |
| * Pull out of band byte out of a segment so |
| * it doesn't appear in the user's data queue. |
| * It is still reflected in the segment length for |
| * sequencing purposes. |
| */ |
| static void |
| tcp_pulloutofband(struct socket *so, struct tcphdr *th, struct mbuf *m, |
| int off) |
| { |
| int cnt = off + th->th_urp - 1; |
| |
| while (cnt >= 0) { |
| if (m->m_len > cnt) { |
| char *cp = mtod(m, caddr_t) + cnt; |
| struct tcpcb *tp = sototcpcb(so); |
| |
| INP_WLOCK_ASSERT(tp->t_inpcb); |
| |
| tp->t_iobc = *cp; |
| tp->t_oobflags |= TCPOOB_HAVEDATA; |
| bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); |
| m->m_len--; |
| if (m->m_flags & M_PKTHDR) |
| m->m_pkthdr.len--; |
| return; |
| } |
| cnt -= m->m_len; |
| m = m->m_next; |
| if (m == NULL) |
| break; |
| } |
| panic("tcp_pulloutofband"); |
| } |
| |
| /* |
| * Collect new round-trip time estimate |
| * and update averages and current timeout. |
| */ |
| static void |
| tcp_xmit_timer(struct tcpcb *tp, int rtt) |
| { |
| int delta; |
| |
| INP_WLOCK_ASSERT(tp->t_inpcb); |
| |
| TCPSTAT_INC(tcps_rttupdated); |
| tp->t_rttupdated++; |
| if (tp->t_srtt != 0) { |
| /* |
| * srtt is stored as fixed point with 5 bits after the |
| * binary point (i.e., scaled by 8). The following magic |
| * is equivalent to the smoothing algorithm in rfc793 with |
| * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed |
| * point). Adjust rtt to origin 0. |
| */ |
| delta = ((rtt - 1) << TCP_DELTA_SHIFT) |
| - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT)); |
| |
| if ((tp->t_srtt += delta) <= 0) |
| tp->t_srtt = 1; |
| |
| /* |
| * We accumulate a smoothed rtt variance (actually, a |
| * smoothed mean difference), then set the retransmit |
| * timer to smoothed rtt + 4 times the smoothed variance. |
| * rttvar is stored as fixed point with 4 bits after the |
| * binary point (scaled by 16). The following is |
| * equivalent to rfc793 smoothing with an alpha of .75 |
| * (rttvar = rttvar*3/4 + |delta| / 4). This replaces |
| * rfc793's wired-in beta. |
| */ |
| if (delta < 0) |
| delta = -delta; |
| delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT); |
| if ((tp->t_rttvar += delta) <= 0) |
| tp->t_rttvar = 1; |
| if (tp->t_rttbest > tp->t_srtt + tp->t_rttvar) |
| tp->t_rttbest = tp->t_srtt + tp->t_rttvar; |
| } else { |
| /* |
| * No rtt measurement yet - use the unsmoothed rtt. |
| * Set the variance to half the rtt (so our first |
| * retransmit happens at 3*rtt). |
| */ |
| tp->t_srtt = rtt << TCP_RTT_SHIFT; |
| tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1); |
| tp->t_rttbest = tp->t_srtt + tp->t_rttvar; |
| } |
| tp->t_rtttime = 0; |
| tp->t_rxtshift = 0; |
| |
| /* |
| * the retransmit should happen at rtt + 4 * rttvar. |
| * Because of the way we do the smoothing, srtt and rttvar |
| * will each average +1/2 tick of bias. When we compute |
| * the retransmit timer, we want 1/2 tick of rounding and |
| * 1 extra tick because of +-1/2 tick uncertainty in the |
| * firing of the timer. The bias will give us exactly the |
| * 1.5 tick we need. But, because the bias is |
| * statistical, we have to test that we don't drop below |
| * the minimum feasible timer (which is 2 ticks). |
| */ |
| TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), |
| max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); |
| |
| /* |
| * We received an ack for a packet that wasn't retransmitted; |
| * it is probably safe to discard any error indications we've |
| * received recently. This isn't quite right, but close enough |
| * for now (a route might have failed after we sent a segment, |
| * and the return path might not be symmetrical). |
| */ |
| tp->t_softerror = 0; |
| } |
| |
| /* |
| * Determine a reasonable value for maxseg size. |
| * If the route is known, check route for mtu. |
| * If none, use an mss that can be handled on the outgoing |
| * interface without forcing IP to fragment; if bigger than |
| * an mbuf cluster (MCLBYTES), round down to nearest multiple of MCLBYTES |
| * to utilize large mbufs. If no route is found, route has no mtu, |
| * or the destination isn't local, use a default, hopefully conservative |
| * size (usually 512 or the default IP max size, but no more than the mtu |
| * of the interface), as we can't discover anything about intervening |
| * gateways or networks. We also initialize the congestion/slow start |
| * window to be a single segment if the destination isn't local. |
| * While looking at the routing entry, we also initialize other path-dependent |
| * parameters from pre-set or cached values in the routing entry. |
| * |
| * Also take into account the space needed for options that we |
| * send regularly. Make maxseg shorter by that amount to assure |
| * that we can send maxseg amount of data even when the options |
| * are present. Store the upper limit of the length of options plus |
| * data in maxopd. |
| * |
| * In case of T/TCP, we call this routine during implicit connection |
| * setup as well (offer = -1), to initialize maxseg from the cached |
| * MSS of our peer. |
| * |
| * NOTE that this routine is only called when we process an incoming |
| * segment. Outgoing SYN/ACK MSS settings are handled in tcp_mssopt(). |
| */ |
| void |
| tcp_mss_update(struct tcpcb *tp, int offer, |
| struct hc_metrics_lite *metricptr, int *mtuflags) |
| { |
| int mss; |
| u_long maxmtu; |
| struct inpcb *inp = tp->t_inpcb; |
| struct hc_metrics_lite metrics; |
| int origoffer = offer; |
| #ifdef INET6 |
| int isipv6 = ((inp->inp_vflag & INP_IPV6) != 0) ? 1 : 0; |
| size_t min_protoh = isipv6 ? |
| sizeof (struct ip6_hdr) + sizeof (struct tcphdr) : |
| sizeof (struct tcpiphdr); |
| #else |
| const size_t min_protoh = sizeof(struct tcpiphdr); |
| #endif |
| |
| INP_WLOCK_ASSERT(tp->t_inpcb); |
| |
| /* Initialize. */ |
| #ifdef INET6 |
| if (isipv6) { |
| maxmtu = tcp_maxmtu6(&inp->inp_inc, mtuflags); |
| tp->t_maxopd = tp->t_maxseg = V_tcp_v6mssdflt; |
| } else |
| #endif |
| { |
| maxmtu = tcp_maxmtu(&inp->inp_inc, mtuflags); |
| tp->t_maxopd = tp->t_maxseg = V_tcp_mssdflt; |
| } |
| |
| /* |
| * No route to sender, stay with default mss and return. |
| */ |
| if (maxmtu == 0) { |
| /* |
| * In case we return early we need to initialize metrics |
| * to a defined state as tcp_hc_get() would do for us |
| * if there was no cache hit. |
| */ |
| if (metricptr != NULL) |
| bzero(metricptr, sizeof(struct hc_metrics_lite)); |
| return; |
| } |
| |
| /* What have we got? */ |
| switch (offer) { |
| case 0: |
| /* |
| * Offer == 0 means that there was no MSS on the SYN |
| * segment, in this case we use tcp_mssdflt as |
| * already assigned to t_maxopd above. |
| */ |
| offer = tp->t_maxopd; |
| break; |
| |
| case -1: |
| /* |
| * Offer == -1 means that we didn't receive SYN yet. |
| */ |
| /* FALLTHROUGH */ |
| |
| default: |
| /* |
| * Prevent DoS attack with too small MSS. Round up |
| * to at least minmss. |
| */ |
| offer = max(offer, V_tcp_minmss); |
| } |
| |
| /* |
| * rmx information is now retrieved from tcp_hostcache. |
| */ |
| tcp_hc_get(&inp->inp_inc, &metrics); |
| if (metricptr != NULL) |
| bcopy(&metrics, metricptr, sizeof(struct hc_metrics_lite)); |
| |
| /* |
| * If there's a discovered mtu int tcp hostcache, use it |
| * else, use the link mtu. |
| */ |
| if (metrics.rmx_mtu) |
| mss = min(metrics.rmx_mtu, maxmtu) - min_protoh; |
| else { |
| #ifdef INET6 |
| if (isipv6) { |
| mss = maxmtu - min_protoh; |
| if (!V_path_mtu_discovery && |
| !in6_localaddr(&inp->in6p_faddr)) |
| mss = min(mss, V_tcp_v6mssdflt); |
| } else |
| #endif |
| { |
| mss = maxmtu - min_protoh; |
| if (!V_path_mtu_discovery && |
| !in_localaddr(inp->inp_faddr)) |
| mss = min(mss, V_tcp_mssdflt); |
| } |
| /* |
| * XXX - The above conditional (mss = maxmtu - min_protoh) |
| * probably violates the TCP spec. |
| * The problem is that, since we don't know the |
| * other end's MSS, we are supposed to use a conservative |
| * default. But, if we do that, then MTU discovery will |
| * never actually take place, because the conservative |
| * default is much less than the MTUs typically seen |
| * on the Internet today. For the moment, we'll sweep |
| * this under the carpet. |
| * |
| * The conservative default might not actually be a problem |
| * if the only case this occurs is when sending an initial |
| * SYN with options and data to a host we've never talked |
| * to before. Then, they will reply with an MSS value which |
| * will get recorded and the new parameters should get |
| * recomputed. For Further Study. |
| */ |
| } |
| mss = min(mss, offer); |
| |
| /* |
| * Sanity check: make sure that maxopd will be large |
| * enough to allow some data on segments even if the |
| * all the option space is used (40bytes). Otherwise |
| * funny things may happen in tcp_output. |
| */ |
| mss = max(mss, 64); |
| |
| /* |
| * maxopd stores the maximum length of data AND options |
| * in a segment; maxseg is the amount of data in a normal |
| * segment. We need to store this value (maxopd) apart |
| * from maxseg, because now every segment carries options |
| * and thus we normally have somewhat less data in segments. |
| */ |
| tp->t_maxopd = mss; |
| |
| /* |
| * origoffer==-1 indicates that no segments were received yet. |
| * In this case we just guess. |
| */ |
| if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && |
| (origoffer == -1 || |
| (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP)) |
| mss -= TCPOLEN_TSTAMP_APPA; |
| |
| #if (MCLBYTES & (MCLBYTES - 1)) == 0 |
| if (mss > MCLBYTES) |
| mss &= ~(MCLBYTES-1); |
| #else |
| if (mss > MCLBYTES) |
| mss = mss / MCLBYTES * MCLBYTES; |
| #endif |
| tp->t_maxseg = mss; |
| } |
| |
| void |
| tcp_mss(struct tcpcb *tp, int offer) |
| { |
| int rtt, mss; |
| u_long bufsize; |
| struct inpcb *inp; |
| struct socket *so; |
| struct hc_metrics_lite metrics; |
| int mtuflags = 0; |
| #ifdef INET6 |
| int isipv6; |
| #endif |
| KASSERT(tp != NULL, ("%s: tp == NULL", __func__)); |
| |
| tcp_mss_update(tp, offer, &metrics, &mtuflags); |
| |
| mss = tp->t_maxseg; |
| inp = tp->t_inpcb; |
| #ifdef INET6 |
| isipv6 = ((inp->inp_vflag & INP_IPV6) != 0) ? 1 : 0; |
| #endif |
| |
| /* |
| * If there's a pipesize, change the socket buffer to that size, |
| * don't change if sb_hiwat is different than default (then it |
| * has been changed on purpose with setsockopt). |
| * Make the socket buffers an integral number of mss units; |
| * if the mss is larger than the socket buffer, decrease the mss. |
| */ |
| so = inp->inp_socket; |
| SOCKBUF_LOCK(&so->so_snd); |
| if ((so->so_snd.sb_hiwat == tcp_sendspace) && metrics.rmx_sendpipe) |
| bufsize = metrics.rmx_sendpipe; |
| else |
| bufsize = so->so_snd.sb_hiwat; |
| if (bufsize < mss) |
| mss = bufsize; |
| else { |
| bufsize = roundup(bufsize, mss); |
| if (bufsize > sb_max) |
| bufsize = sb_max; |
| if (bufsize > so->so_snd.sb_hiwat) |
| (void)sbreserve_locked(&so->so_snd, bufsize, so, NULL); |
| } |
| SOCKBUF_UNLOCK(&so->so_snd); |
| tp->t_maxseg = mss; |
| |
| SOCKBUF_LOCK(&so->so_rcv); |
| if ((so->so_rcv.sb_hiwat == tcp_recvspace) && metrics.rmx_recvpipe) |
| bufsize = metrics.rmx_recvpipe; |
| else |
| bufsize = so->so_rcv.sb_hiwat; |
| if (bufsize > mss) { |
| bufsize = roundup(bufsize, mss); |
| if (bufsize > sb_max) |
| bufsize = sb_max; |
| if (bufsize > so->so_rcv.sb_hiwat) |
| (void)sbreserve_locked(&so->so_rcv, bufsize, so, NULL); |
| } |
| SOCKBUF_UNLOCK(&so->so_rcv); |
| /* |
| * While we're here, check the others too. |
| */ |
| if (tp->t_srtt == 0 && (rtt = metrics.rmx_rtt)) { |
| tp->t_srtt = rtt; |
| tp->t_rttbest = tp->t_srtt + TCP_RTT_SCALE; |
| TCPSTAT_INC(tcps_usedrtt); |
| if (metrics.rmx_rttvar) { |
| tp->t_rttvar = metrics.rmx_rttvar; |
| TCPSTAT_INC(tcps_usedrttvar); |
| } else { |
| /* default variation is +- 1 rtt */ |
| tp->t_rttvar = |
| tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE; |
| } |
| TCPT_RANGESET(tp->t_rxtcur, |
| ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, |
| tp->t_rttmin, TCPTV_REXMTMAX); |
| } |
| if (metrics.rmx_ssthresh) { |
| /* |
| * There's some sort of gateway or interface |
| * buffer limit on the path. Use this to set |
| * the slow start threshhold, but set the |
| * threshold to no less than 2*mss. |
| */ |
| tp->snd_ssthresh = max(2 * mss, metrics.rmx_ssthresh); |
| TCPSTAT_INC(tcps_usedssthresh); |
| } |
| if (metrics.rmx_bandwidth) |
| tp->snd_bandwidth = metrics.rmx_bandwidth; |
| |
| /* |
| * Set the slow-start flight size depending on whether this |
| * is a local network or not. |
| * |
| * Extend this so we cache the cwnd too and retrieve it here. |
| * Make cwnd even bigger than RFC3390 suggests but only if we |
| * have previous experience with the remote host. Be careful |
| * not make cwnd bigger than remote receive window or our own |
| * send socket buffer. Maybe put some additional upper bound |
| * on the retrieved cwnd. Should do incremental updates to |
| * hostcache when cwnd collapses so next connection doesn't |
| * overloads the path again. |
| * |
| * RFC3390 says only do this if SYN or SYN/ACK didn't got lost. |
| * We currently check only in syncache_socket for that. |
| */ |
| #define TCP_METRICS_CWND |
| #ifdef TCP_METRICS_CWND |
| if (metrics.rmx_cwnd) |
| tp->snd_cwnd = max(mss, |
| min(metrics.rmx_cwnd / 2, |
| min(tp->snd_wnd, so->so_snd.sb_hiwat))); |
| else |
| #endif |
| if (V_tcp_do_rfc3390) |
| tp->snd_cwnd = min(4 * mss, max(2 * mss, 4380)); |
| #ifdef INET6 |
| else if ((isipv6 && in6_localaddr(&inp->in6p_faddr)) || |
| (!isipv6 && in_localaddr(inp->inp_faddr))) |
| #else |
| else if (in_localaddr(inp->inp_faddr)) |
| #endif |
| tp->snd_cwnd = mss * V_ss_fltsz_local; |
| else |
| tp->snd_cwnd = mss * V_ss_fltsz; |
| |
| /* Check the interface for TSO capabilities. */ |
| if (mtuflags & CSUM_TSO) |
| tp->t_flags |= TF_TSO; |
| } |
| |
| /* |
| * Determine the MSS option to send on an outgoing SYN. |
| */ |
| int |
| tcp_mssopt(struct in_conninfo *inc) |
| { |
| int mss = 0; |
| u_long maxmtu = 0; |
| u_long thcmtu = 0; |
| size_t min_protoh; |
| |
| KASSERT(inc != NULL, ("tcp_mssopt with NULL in_conninfo pointer")); |
| |
| #ifdef INET6 |
| if (inc->inc_flags & INC_ISIPV6) { |
| mss = V_tcp_v6mssdflt; |
| maxmtu = tcp_maxmtu6(inc, NULL); |
| thcmtu = tcp_hc_getmtu(inc); /* IPv4 and IPv6 */ |
| min_protoh = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); |
| } else |
| #endif |
| { |
| mss = V_tcp_mssdflt; |
| maxmtu = tcp_maxmtu(inc, NULL); |
| thcmtu = tcp_hc_getmtu(inc); /* IPv4 and IPv6 */ |
| min_protoh = sizeof(struct tcpiphdr); |
| } |
| if (maxmtu && thcmtu) |
| mss = min(maxmtu, thcmtu) - min_protoh; |
| else if (maxmtu || thcmtu) |
| mss = max(maxmtu, thcmtu) - min_protoh; |
| |
| return (mss); |
| } |
| |
| |
| /* |
| * On a partial ack arrives, force the retransmission of the |
| * next unacknowledged segment. Do not clear tp->t_dupacks. |
| * By setting snd_nxt to ti_ack, this forces retransmission timer to |
| * be started again. |
| */ |
| static void |
| tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th) |
| { |
| tcp_seq onxt = tp->snd_nxt; |
| u_long ocwnd = tp->snd_cwnd; |
| |
| INP_WLOCK_ASSERT(tp->t_inpcb); |
| |
| tcp_timer_activate(tp, TT_REXMT, 0); |
| tp->t_rtttime = 0; |
| tp->snd_nxt = th->th_ack; |
| /* |
| * Set snd_cwnd to one segment beyond acknowledged offset. |
| * (tp->snd_una has not yet been updated when this function is called.) |
| */ |
| tp->snd_cwnd = tp->t_maxseg + (th->th_ack - tp->snd_una); |
| tp->t_flags |= TF_ACKNOW; |
| (void) tcp_output(tp); |
| tp->snd_cwnd = ocwnd; |
| if (SEQ_GT(onxt, tp->snd_nxt)) |
| tp->snd_nxt = onxt; |
| /* |
| * Partial window deflation. Relies on fact that tp->snd_una |
| * not updated yet. |
| */ |
| if (tp->snd_cwnd > th->th_ack - tp->snd_una) |
| tp->snd_cwnd -= th->th_ack - tp->snd_una; |
| else |
| tp->snd_cwnd = 0; |
| tp->snd_cwnd += tp->t_maxseg; |
| } |